Prep the chicken: Pat the chicken dry and slice into thin strips. This helps it cook fast and stay tender.
Mix the seasoning: In a small bowl, combine chili powder, cumin, smoked paprika, garlic powder, onion powder, oregano, red pepper flakes (if using), salt, and black pepper.
Season the chicken: Toss the chicken with half the seasoning and 1 tablespoon of oil until well coated.
Sear the chicken: Heat a large skillet over medium-high.
Add the chicken in a single layer. Cook 5–7 minutes, stirring once or twice, until cooked through with some browned edges. Transfer to a plate.
Cook the veggies: In the same skillet, add the remaining 1 tablespoon oil.
Add the peppers and onion, sprinkle with the rest of the seasoning, and sauté 5–7 minutes until tender-crisp with some char.
Combine and finish: Return the chicken to the skillet. Add lime juice and toss for 1 minute to warm through and brighten the flavors. Taste and adjust salt or heat.
Assemble the bowls: Add lettuce or cauliflower rice to each bowl.
Top with the chicken and fajita veggies.
Add toppings: Finish with avocado, cheese, sour cream or yogurt, cilantro, a squeeze of lime, and a spoon of sugar-free salsa.
Serve: Enjoy warm. Add extra lime or hot sauce if you like it zesty.