Wash potatoes and place in a large stockpot. Cover with cold water, bring to a boil and let cook until just done, about 15-20 minutes. Drain, allow to cool to the touch. Cut in half lengthwise. Set aside.
Season steak with blackening seasoning. Set aside.
Prepare grill. Right before grilling the potatoes, toss them in the olive oil, salt, and pepper to taste. Grill over high heat, turning to achieve grill marks. Take off the grill, set aside and allow to cool completely.
Grill flank to the desired doneness. Cook corn at the same time, allowing to get charred on all sides. Take off the grill, set aside and allow to cool completely.
Place potatoes, steak, and corn in the refrigerator until cold, about 2 hours.
Cut steak thinly on a bias. Cut corn off the cob. Seed tomato and cut into large chunks. Thinly slice scallions.
Add the potatoes, steak, corn, tomatoes, scallions and bleu cheese crumbles to a large bowl. Add Bleu Cheese Dressing to coat, taste, adjust seasoning if needed. Serve and enjoy!