Whisk the marinade ingredients, including 2 tablespoons oil and ½ teaspoon salt.
One at a time, place each chicken breast, smooth side down, on a cutting board. Place a sheet of plastic wrap over the chicken and pound to an even 12-millimeter thickness. Place the chicken in a large resealable plastic bag and pour in the marinade. Press the air out of the bag and seal tightly. Turn the bag to distribute the marinade, place in a bowl, and refrigerate for 2 to 4 hours.
Prepare the grill for direct cooking over medium heat (180° to 230°C).
Prepare the grill for cooking over medium heat (200°C).
Lightly brush the bell peppers and onions with oil and season evenly with salt and pepper. Grill the vegetables over direct medium heat, with the lid closed, until tender, turning once or twice. The bell peppers will take 6 to 8 minutes and the onions will take 10 to 12 minutes. Remove from the grill, cut the bell peppers into 2.5-centimeter strips, separate the onions into rings, place in a bowl, and keep warm.
Lightly brush the bell peppers and onions with oil and season evenly with salt and pepper. Grill the vegetables over medium heat, with the lid closed, until tender, turning once or twice. The bell peppers will take 6 to 8 minutes and the onions will take 10 to 12 minutes. Remove from the grill, cut the bell peppers into 2.5-centimeter strips, separate the onions into rings, place in a bowl, and keep warm.
Wrap six tortillas in each of two foil packets.
Remove the chicken from the bag and discard marinade. Grill the chicken over direct medium heat, with the lid closed, until firm to the touch and opaque all the way to the center, 6 to 8 minutes, turning once. At the same time, warm the tortilla packets over direct heat for 2 to 4 minutes, turning once or twice.
Remove the chicken from the bag and discard marinade. Grill the chicken over medium heat, with the lid closed, until firm to the touch and opaque all the way to the center, 6 to 8 minutes, turning once. At the same time, warm the tortilla packets over direct heat for 2 to 4 minutes, turning once or twice.
Cut the chicken crosswise into 6-millimeter strips and add to the bowl with the bell peppers and onions. Add the cilantro and stir to combine. Serve the warm chicken mixture in tortillas with lime wedges, sour cream, and salsa.
