1/3 cup freshly squeezed lime juice
6 tbsp. vegetable oil, divided
3 cloves garlic, minced or pressed
1 tbsp. Worcestershire sauce
1½ tsp. brown sugar
1 jalapeño, seeded, ribbed and diced
1½ tbsp. minced fresh cilantro
1 tsp. salt
¾ tsp. pepper
2-3 boneless, skinless chicken breasts, butterflied (6 halves total), about 1½ lbs.
1 large red onion (about 14 oz.), sliced into ½-inch thick slices, rings not separated
2 large bell peppers (about 10 oz. each), stemmed, quartered and seeded
8-12 (6-inch) flour tortillas
In a medium bowl, whisk together the lime juice, 4 tablespoons of the vegetable oil, garlic, Worcestershire sauce, brown sugar, jalapeño, cilantro, salt and pepper. Reserve ¼ cup of the marinade; set aside. Place the chicken breast halves in the marinade, cover with plastic wrap and refrigerate for 15 minutes. Brush both sides of the onion rounds and peppers with the remaining 2 tablespoons vegetable oil. Season with salt and pepper.
Meanwhile, using a large chimney starter, ignite 6 quarts of charcoal briquettes and burn until the coals are fully ignited, about 20 minutes. Empty the coals into the grill, spreading them in a single layer. Place an additional 20 unlit coals over the lit coals on one side of the grill to create a tw0-level fire. Place the grill grate over the coals and allow to heat for 5 minutes. Scrape the grate clean with a grill brush. (For a gas grill, light all burners to high, cover and heat grill until hot, about 15 minutes. Leave one burner on high and turn the rest down to medium.)
Remove the chicken breast halves from the marinade and transfer to the hotter side of the grill; discard the left over marinade. Place the onion rounds and peppers on the cooler side of the grill. Cook the chicken until it is well browned, 3-4 minutes. Using tongs, flip the chicken and continue grilling until it is no longer pink inside (or an instant-read thermometer inserted into the center reads 160˚ F.) Meanwhile, cook onions and peppers until spottily charred and crisp-tender, about 8-12 minutes, turning once or twice as needed. When the chicken and vegetables are done, transfer them to a large plate and tent with foil to keep warm.
In 2 or 3 batches, transfer the tortillas in a single layer to the now empty grill on the cooler side. Cook until warm and lightly browned, about 20 seconds per side. When the tortillas are done, wrap them in a clean kitchen towel or foil.
Separate the onions into rings and place them in a medium bowl. Slice the bell peppers lengthwise into ¼-inch strips and add them to the bowl with the onions. Add 2 tablespoons of the reserved unused marinade and toss well to combine. Slice the chicken into ¼-inch strips and toss with the remaining 2 tablespoons of reserved marinade in another bowl. Arrange the chicken and vegetables on a large platter with the warmed tortillas and serve.