1-Combine the marinade ingredients in a medium bowl. Slice the chicken breast lengthwise to about 1/2 inch thickness, add it to the marinade, and stir to coat evenly. Cover and refrigerate for 45 minutes to 1 hour, stirring midway.

2-To cook the chicken, either grill it by preheating to medium/low heat (about 350°F) and cooking for 6-8 minutes per side, rotating once, or sauté it in a large skillet over medium heat with 1-2 tablespoons oil until browned and cooked through, about 3 minutes per side.

3-For the vegetables, use the same pan to sauté the mushrooms with 1-2 tablespoons oil until browned, then remove and set aside. Next, sauté the onions and bell peppers with 1-2 tablespoons oil, stirring every 2 minutes for about 8 minutes to sear and brown the edges. Season with salt and pepper.

4-Assemble the fajitas by slicing the cooked chicken into 1/4 inch strips and layering it over the vegetables. Top with the mushrooms, shredded cheese, and crumbled bacon. Place under a broiler for 2-3 minutes until the cheese melts.

5-Warm the tortillas by wrapping them in a damp paper towel and microwaving for 45 seconds to 1 minute. Keep them covered until ready to assemble.

6-To serve, spread sour cream and guacamole on the warm tortillas, add lettuce, then the chicken and vegetable mixture, and finish with salsa or hot sauce.