Season chicken on both sides with salt and pepper. Heat the oil in a stock pot over medium high heat and sear the chicken on both sides. Set aside, it doesn't have to be cooked through.
Add garlic to the pot and let saute until aromatic, about 20 seconds. Add in the 2 quarts of the chicken stock and put the chicken back in the pot. Cover and let simmer for about 30 minutes or until the chicken is cooked through to 165 degrees. Take the chicken out of the pot.
Mix the masa harina a little at a time with the remaining stock and add to the pot with the rest of the ingredients except for the chicken and garnishes.
Slice the chicken and add to the pot, bring to a simmer and let cook for about 30 minutes or until thickened. Stirring occasionally to make sure the bottom doesn't burn, make sure to scrap the bottom of the pan.
Serve with garnishes and enjoy!