Preheat grill to medium-high heat. Puree cilantro, olive oil, lime juice, garlic, cumin, and chili powder in a blender or food processor. Place chicken in a glass baking dish and pour ? of marinade over chicken, turning to coat all sides. Season with salt and pepper, if desired. Transfer chicken to barbecue. Grill chicken until cooked through (7-10 minutes per side, depending on thickness of chicken).
While chicken is cooking, slice and prepare vegetables. Arrange vegetables (chilies, red pepper, and onions) on a rimmed grilling or baking pan; pour ? of marinade over vegetables. Season with salt and pepper, if desired.
Remove cooked chicken from grill and transfer to a work surface. Grill vegetables until tender, turning often (about 15 minutes). Meanwhile, slice chicken cross-wise into strips.
Grill tortillas until charred (1 minute per side). Fill tortillas with chicken and vegetables and drizzle with remaining marinade. Serve with your favorite salsa and toppings.
This Grilled Chicken Fajitas recipe is from the 101 Things To Do With A Casserole Cookbook. Download this Cookbook today.