Preheat oven to 425°F (220°C).
Prep your ingredients: Place the chicken fillets and sliced bell peppers on a sheet pan. Drizzle with olive oil, then sprinkle on taco seasoning, garlic plus, salt, pepper, and cayenne. Toss everything together right on the pan to coat evenly.
Bake: Spread everything out in a single layer. Bake for about 15–17 minutes, or until the chicken is cooked through and the peppers are tender and a little charred.
Slice chicken (if needed): If your fillets are whole, let them rest for a minute, then slice into strips.
Warm your tortillas: While everything's baking, warm your tortillas in a dry skillet or microwave.
Assemble & serve: Load up your tortillas with the chicken and peppers, and add your favourite toppings.