In a resealable plastic bag, combine
chicken, lime juice, garlic, and jalapeño; turn to coat well. Marinate chicken
at room temperature for 20 minutes or refrigerate overnight.
Remove chicken from marinade, discarding leftover marinade, and
season lightly with salt and black pepper. Lightly coat a grill or grill pan
with cooking spray and heat to medium-high. Grill chicken until cooked through,
about 5 minutes per side. Transfer to a cutting board.
While chicken is cooking, in a
medium bowl toss bell peppers and onion with oil. Using a grill basket or grill
topper, if necessary, grill vegetables, turning occasionally, until softened
and lightly charred, 15 to 20 minutes. Transfer onions to a platter. Transfer
peppers to a cutting board and cut into thin strips; transfer to the platter
Grill tortillas until warm and
lightly browned, about 30 seconds per side. Wrap in foil to keep warm. Slice
chicken breasts into 1⁄2-inch-thick pieces. Place on the platter with
vegetables and serve with warmed tortillas.