Combine the 4 chicken breasts, juice from 1 lime, the 1/2 cup chopped cilantro, the 2 cloves chopped garlic, the 1/2 teaspoon ground coriander, the 1/2 teaspoon pepper, the 1 teaspoon dried oregano, the 1 teaspoon salt, the 1 teaspoon cumin, and 2 tablespoons of the olive oil in a large bowl and toss to coat chicken breasts. Cover and refrigerate at least an hour or up to a day in advance. 

30 minutes before grilling remove chicken from the refrigerator. Heat outdoor grill over medium-high heat. Clean and brush grates with oil. While grill is heating, toss the 1 large onion, red and green peppers, and whole jalapenos in the remaining tablespoon of olive oil and season well with salt and pepper.

Place the chicken on the preheated grill, draining & discarding any excess marinade. Grill the chicken for 5-6 minutes per side, or until cooked through with beautifully charred grill marks. Transfer to a plate or small baking sheet and cover with foil to keep warm while the vegetables cook.

Place vegetables on the grill, turning every few minutes, until tender, about 10 minutes total. Slice chicken and vegetables into thin strips. Serve with warm tortillas, avocado slices and lime wedges.