Preheat oven to 425°F/218° degrees. Place large, rimmed baking sheet in oven to preheat.
In large bowl, whisk together oil, lime juice, taco seasoning, salt and cayenne pepper or hot pepper flakes.
Add chicken strips, onions and peppers to bowl and mix well to coat all ingredients evenly.
Carefully remove hot baking sheet from oven. Use a spatula to spread chicken and vegetables evenly on the hot pan. Return to oven and bake for 15-20 minutes until meat thermometer reads 165°F/74°C. To check, slide tip of thermometer into the thickest part of the thickest piece of chicken. If ready, remove from oven and let stand 5 minutes. If not ready, continue baking for 5 minutes and check temperature again.
To warm tortillas, wrap in foil and place in oven during the last five minutes of cooking.
Transfer to serving platter or serve right off the baking sheet to save even more dishes!
Let everyone assemble their own fajitas with optional fresh garnishes like shredded cabbage, shredded lettuce, shredded carrots, sliced radishes, sliced avocado, chopped cilantro, sour cream, shredded cheddar, Queso Fresco, Cotija or Feta cheese, avocado lime sauce, salsa, guacamole and lime wedges. Whatever you have on that looks appealing to you!
Leftovers taste great hot or cold! Store in a covered container in the fridge for 3 to 4 days.Taco Seasoning Substitute: Mix together 1 tsp chili powder, 1/2 tsp cumin, 1/4 tsp paprika, 1/4 tsp oregano, 1/4 tsp garlic powder, 1/4 tsp black pepper, dash cayenne pepper.