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Crispy Onion Petals (Outback Bloom Sauce) are the steakhouse appetizer your weekend was made for, sweet onion wedges double-dredged in seasoned flour and a buttermilk bath, then deep fried at 350F until they shatter on the first bite. The copycat bloom sauce whisks together in 60 seconds from pantry staples, the fryer does the rest of the work. If you love the marinated grilled flank steak we make on date night, these crispy Onion Petals are the appetizer that belongs on the same plate.
One sweet onion, a hot fryer, and a tangy mayo-horseradish-ketchup sauce stand between you and a steakhouse-quality appetizer you can plate in under 20 minutes.
Onion Petals Quick Look
- 🕐 Prep Time: 15 minutes
- 🍴 Cook Time: 4 minutes per batch
- ⏳ Total Time: 19 minutes
- 🍽 Servings: 4 appetizer servings
- ⚡ Calories: Approximately 380 kcal per serving
- 🌶 Flavor Profile: Sweet onion, salty seasoned crust, tangy mayo-horseradish bloom sauce with a cayenne kick (copycat Outback appetizer).
- ✋ Difficulty: Easy, on par with our other party appetizer recipes.
Quick Answer
The double-dredge sequence is the secret, seasoned flour, then a buttermilk and egg wet bath, then back into the seasoned flour, then fry at 350F in neutral oil. The two flour layers build the shattering crust, the buttermilk locks in moisture, and the 350F oil temperature is hot enough to set the crust before the breading absorbs grease. Salt the petals the second they hit paper towels and serve within 10 minutes for peak crunch.
Jump to:
Why This Recipe Works
Click to see the technique science
- Double-dredge breading. The flour, buttermilk, flour sequence is non-negotiable. The first flour layer dries the petal so the wet batter clings. The wet bath glues the second flour layer on. Two crust layers fry into a shattering shell instead of a wet, soggy single coat.
- 350F oil temperature. Hot enough to flash-set the breading before it absorbs grease, low enough that the sweet onion cooks through in 3 to 4 minutes without burning the crust. A clip-on thermometer pays for itself the first time you use it.
- Sweet onion not yellow. Vidalia, Walla Walla, or Maui sweet onions carry enough natural sugar to caramelize lightly under the crust and stay mild after frying. A standard yellow onion fries up bitter and overpowers the bloom sauce.
- Buttermilk plus egg wet bath. Buttermilk tenderizes and adds tang, the egg locks the second flour layer in place. Skipping the egg gives a flaky but loose crust that falls off when you dip.
- Cayenne in both the dredge and the sauce. Tiny amount in each layer builds heat that hits in waves, dredge first, sauce second. Single-layer cayenne is one-note.
Why You’ll Love This Recipe
- Better than the restaurant. You control the salt, the oil freshness, and the sauce ratio. One sweet onion costs less than a single appetizer order.
- Under 20 minutes total. Sauce while the oil heats, dredge while the first batch cooks, serve before the cocktails get warm.
- Pantry-friendly. Flour, buttermilk, egg, sweet onion, plus the spice rack you already own. The sauce uses mayo, sour cream, ketchup, and horseradish.
- Party-friendly. Doubles or triples without changing the technique. Keep batches warm in a 200F oven on a wire rack so they stay crisp.
- Steakhouse vibes at home. Plates beautifully next to a ribeye or a thick smash burger, no carving project required.
Key Ingredients
- Sweet onion: 1 large. Vidalia, Walla Walla, or Maui. The natural sugar mellows under the crust and stays mild after frying.
- All-purpose flour: 2 cups. The double-dredge backbone. Build a seasoned flour station once, use it twice.
- Buttermilk: 1 cup. Tang plus tenderness. No buttermilk? Stir 1 tablespoon white vinegar into 1 cup whole milk and rest 5 minutes.
- Egg: 1 large. The wet-bath glue that locks the second flour layer in place.
- Seasoned salt, paprika, garlic powder, onion powder, cayenne, black pepper: the seasoned-flour spice rack. Cayenne pulls double duty in the sauce too.
- Mayonnaise: 1/2 cup. The body of the copycat Outback bloom sauce.
- Sour cream: 2 tablespoons. Tang plus body. Lightens the mayo without thinning the sauce.
- Ketchup: 2 tablespoons. Adds the signature pink color and a sweet-acidic counterweight to the horseradish.
- Prepared horseradish: 1 tablespoon. The bite that makes this taste like Outback. Sharp jarred horseradish, not creamy horseradish sauce.
- Neutral frying oil: 2 inches in a Dutch oven or countertop fryer. Canola, vegetable, or peanut. Heated to 350F.
See the recipe card below for exact quantities and the full ingredient list.
Variations and Substitutions
One base recipe, six ways to switch up the bite or the heat.
- Air fryer Onion Petals: mist the dredged petals heavily with neutral oil, air fry at 400F for 8 to 10 minutes, shaking the basket once at the 5-minute mark. Not as shattering as deep-fried but excellent.
- Spicy bloom sauce: double the cayenne and stir in a teaspoon of your favorite hot sauce, smoked chipotle hot sauce is fantastic.
- Gluten-free: swap the all-purpose flour for a 1:1 gluten-free baking blend. Bobs Red Mill or King Arthur Measure for Measure both fry up crisp.
- Yellow onion swap: a yellow or white onion will work in a pinch. Add an extra tablespoon of granulated sugar to the dredge to balance the sharper flavor.
- Ranch dipping sauce: prefer cool to kicky? Skip the horseradish and stir in a tablespoon of our homemade ranch dressing mix instead.
- Smoky paprika version: swap regular paprika for smoked paprika in the dredge for a campfire-leaning bloom flavor.
How to Make Onion Petals
- Whisk the mayo, sour cream, ketchup, horseradish, cayenne, garlic powder, onion powder, smoked paprika, salt, and pepper together in a small bowl. Cover and refrigerate while you fry, the sauce gets better as the flavors meld.
- Slice the top off a large sweet onion, peel it, and stand it root-side up. Slice down toward the root in eight wedges, leaving the root attached so the wedges hold together while you work.
- Gently break the wedges into individual petals over a parchment-lined sheet pan. Two to three layers of petals deep is fine, you will dredge each one in a moment.
- Whisk the flour, seasoned salt, paprika, garlic powder, onion powder, cayenne, and black pepper together in a large bowl. Toss a handful of petals in the seasoned flour, tap off the excess, and set aside.
- Whisk the buttermilk and egg together in a second bowl. Dip the floured petals into the buttermilk wet bath one batch at a time, letting the excess drip back into the bowl.
- Return the wet petals to the seasoned flour and coat them a second time. Tap off excess and arrange the breaded petals in a single layer on a parchment-lined sheet pan.
- Heat 2 inches of neutral oil to 350F in a Dutch oven, deep skillet, or countertop fryer. Fry the petals in batches of two layers max, 3 to 4 minutes per batch, until shatteringly golden brown.
- Transfer fried petals to a paper-towel-lined sheet pan and season them immediately with seasoned salt while the oil sheen is still wet. Salt clings to the hot surface and locks in flavor.
- Pile the crispy Onion Petals on a platter, set the chilled bloom sauce in the middle, and serve immediately. Add a wedge of lemon on the side for a bright optional accent.
Recipe Tips & Tricks
Five moves that separate shattering, golden brown Onion Petals from soggy, greasy ones.
- Oil thermometer non-negotiable. 350F is the sweet spot. Below 325F the breading absorbs grease, above 375F the crust burns before the onion cooks. A 10 dollar clip-on candy thermometer fixes everything.
- Tap off the excess flour. A quick shake before the wet bath keeps the buttermilk from gumming up with loose flour, which turns the second dredge into a pasty crust.
- Salt the second they hit paper towels. Hot, oily petals grab salt instantly. Wait 30 seconds and the surface dries and the salt slides off.
- Two layers per batch max. Crowding drops the oil temperature, steams the breading, and you end up with limp, pale petals. Patience pays off here.
- Bloom sauce the night before. Whisking the sauce 12 to 24 hours ahead lets the horseradish, garlic, and cayenne marry into the mayo. Friday-night cook, Saturday-night serve.
Serving Ideas and Suggestions
- Serve as a steakhouse-style appetizer next to a thick-cut ribeye or our marinated grilled flank steak for the full Outback-at-home night.
- Plate alongside jalapeno popper cream cheese pinwheels and a stack of buffalo wings for the ultimate game day appetizer board.
- Swap fries for Onion Petals next to a smash burger or a Philly cheesesteak hoagie for a fast-food upgrade.
- Pile them in the center of the table family-style with three ramekins of bloom sauce so everyone can dip without crowding one bowl.
- Pair with a cold pilsner, a classic margarita on the rocks, or an ice-cold sweet tea, the salt and crunch cut through any drink.
Fry up a batch of these crispy Onion Petals this weekend and tell us how the copycat bloom sauce came out. Tag us on Instagram @ThisSillyGirlsKitchen, leave a star rating below, and let us know what you served them with.
Onion Petals FAQs
A Bloomin Onion is a single whole carved onion fried bloom-side up, the version made famous by Outback Steakhouse. Onion Petals are the same flavors broken into individual fryable wedges, easier to make at home, easier to share at a party, and no carving project required. The bloom sauce that comes with both is identical.
Copycat Outback bloom sauce. Whisk together mayonnaise, sour cream, ketchup, prepared horseradish, cayenne, garlic powder, onion powder, smoked paprika, salt, and pepper. Make it the night before for the strongest flavor, the horseradish and cayenne marry into the mayo overnight.
Yes. Mist the dredged petals heavily with neutral oil, then air fry at 400F for 8 to 10 minutes, shaking the basket once at the 5-minute mark. The crust will not be quite as shatteringly crispy as deep-fried but still excellent for a lighter version.
Neutral high-smoke-point oils: canola oil, vegetable oil, or peanut oil. Heat to 350F. A clip-on candy thermometer or countertop fryer makes hitting and holding 350F simple. Avoid olive oil, butter, or anything with a strong flavor or low smoke point.
Store cooled leftovers in an airtight container in the fridge for up to 3 days. Reheat at 400F in the oven or air fryer for 4 to 6 minutes until crisp again. Skip the microwave or they will go soggy. The bloom sauce holds for up to 5 days refrigerated.
Yes in a pinch. The flavor will be sharper and slightly bitter so add an extra tablespoon of granulated sugar to the seasoned flour to balance. Vidalia, Walla Walla, and Maui sweet onions all carry enough natural sugar to fry up mild without any adjustment.
Other Recommended Copycat Recipes
If you made these Crispy Onion Petals, leave a star rating and a comment below. We love hearing how your batch turned out. Tag us on Instagram @ThisSillyGirlsKitchen so we can see your appetizer plates and bloom sauce ramekins.
Plate the steakhouse appetizer alongside our Cold Green Bean Salad Recipe (Marinated with Tomatoes) for a fresh contrast.
Build a full fried-appetizer board by pairing onion petals with our restaurant-style Deep Fried Potato Wedges for golden crispy wedges in 18 minutes.
For a full crunchy appetizer-and-main spread, our crispy fried catfish recipe for golden cornmeal crusted catfish in under 20 minutes.
Crispy Onion Petals Recipe (Outback Bloom Sauce)
Ingredients
For the bloomin' sauce
- 1/2 cup mayonnaise
- 1/4 cup sour cream
- 2 tablespoons ketchup
- 2 tablespoons prepared horseradish
- 1 clove garlic minced
- 1/2 teaspoon kosher salt
- 1/4 teaspoon black pepper
- 1/4 teaspoon smoked paprika
- pinch cayenne pepper
For the onions
- 1 large sweet onion
- 2 cups all-purpose flour
- 2 teaspoons seasoned salt
- 1/2 teaspoon black pepper
- 1/2 teaspoon garlic powder
- 1/2 teaspoon cayenne
- 1/2 teaspoon onion powder
- 1/2 teaspoon smoked paprika
- 1 cup buttermilk
- 1 large egg
- oil for frying
Instructions
For the bloomin' sauce
- Make the sauce first by whisking together the mayonnaise, sour cream, ketchup, horseradish, garlic, salt, pepper, paprika, and cayenne until smooth. Cover with plastic wrap and place in the fridge until serving.
For the onions
- Cut the root off of the onion and discard the peel. Cut the onion in half, then into 4ths. Cut the wedges again in half, and set aside.
- In a large bowl, stir together the flour, seasoned salt, black pepper, garlic powder, cayenne, onion powder, and smoked paprika.
- In another medium-sized bowl, whisk together the buttermilk and egg.
- Separate the onion petals and place them into a gallon-sized zipper bag. Add ¼ cup of the flour mixture to the bag. Seal the bag and toss the onion petals in the flour.
- Taking a handful of the petals at a time, tap off the excess flour. Dip them into the buttermilk mixture. Let any excess drip off.
- Add the petals directly to the bowl with the flour mixture and coat them well, tap off any excess.
- Place the petals onto a parchment-lined sheet tray and continue coating the rest of the petals.
- Heat your deep fryer or large skillet with deep sides with 2 inches of oil to 350°F. Once hot, dry the prepared onion petals for 3-4 minutes until golden brown.
- Place the fried petals onto a paper towel-lined plate to absorb any excess oil. Then, place them on a wire rack over a sheet tray while you fry the remaining petals, so they don’t become soggy.
- Once all of the petals are done frying, serve them with the sauce and enjoy.
Notes
- Add more cayenne or hot sauce to amp up the heat.
- This can be frozen before or after frying, see above on how to do that.
- This can easily be doubled or tripled.
- Use a sweet onion if you can, if not, a white or yellow onion will work.
- Make the sauce the day before if time allows.
Nutrition
Love This Recipe?
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This is by far the best recipe I have used/found!! Delicious!!!
Loving them. Thank you for the recipe.
Can I make these in my basket air fryer? If so, at what temp and for how long?