In a food processor, place the scallions, garlic, onion, cilantro, thyme, vinegar, cumin, paprika, salt and pepper. Process to a paste.
Place the chicken in a zip -bag and add the marinade. Move around to cover evenly. Refrigerate the chicken overnight.
Cover a baking sheet with foil and coat with cooking spray. Position an oven rack in the center of the oven and heat the broiler to high.
Place the chicken legs on the baking sheet. Broil for about 10 minutes and turn the legs one time and cook for 12 to 15 minutes more or until the chicken is cooked and the skin is browned. Let it rest for 5 minutes and transfer to a serving plate.