In a medium bowl, combine juice of oranges and limes with olive oil, garlic salt, garlic powder, pepper, cumin and smoked paprika. Stir well.
Place meat in a gallon sized plastic bag with peppers and garlic. Pour marinade in the bag, seal the bag and gently massage the marinade on the meat and peppers.
Place bag in refrigerator and marinate for up to 12 hours.
Preheat oven to 400°F. Line a baking sheet with foil and layer peppers and meat on the baking sheet. Pour remaining marinade from bag over meat and pepper mixture. Top with cilantro, if preferred.
Bake for 25 minutes.
Remove from oven, allow meat to cool, then slice and serve with tortillas and preferred toppings.
