In a zip lock bag combine olive oil, chili power, ground cumin, crushed red pepper flakes, salt, pepper, white sugar, Worcestershire sauce, minced garlic, and fresh lime juice
Add chicken breasts to marinade. Let marinate in the fridge at least 4 hours, preferably overnight
Preheat skillet or outdoor grill to medium heat. If using skillet, add 1 tbsp olive oil to pan. Remove chicken from marinade and cook about 7-8 minutes per side until golden brown. Meanwhile cook sliced green peppers and onions for 8 minutes or until soft.
Allow cooked chicken to rest about 5 minutes then slice into strips. Serve chicken, onion, and green peppers over tortillas. Add toppings of choice