Combine garlic, sea salt, pepper, cumin, lime juice, oil and cilantro in a non-reactive container, such as glass. Add meat to marinade and turn to coat well. Marinate for at least 1 hour at room temperature or overnight in the refrigerator, turning occasionally.
Preheat the grill to medium heat. Remove chicken from refrigerator 30 minutes before grilling. Grill chicken a few minutes on each side until cooked through.
Heat oil in a large skillet over medium heat. Add peppers, onion and garlic. Season with salt and pepper to taste. Saute the mixture, stirring, for 10-12 minutes, or until softened. You can add the cooked, sliced meat to the vegetable mixture and combine everything or serve both separately.
Warm tortillas on both sides over medium heat on a griddle pan. Or if you are heat a large amount, wrap the entire stack in parchment paper, then aluminum foil and heat through in a 350 degree oven. Serve with desired accompaniments.