Mix the seasoning: In a small bowl, stir together chili powder, cumin, smoked paprika, garlic powder, onion powder, oregano, salt, pepper, and cayenne if using.
Season the chicken: Pat chicken dry.
Toss with 1 tablespoon olive oil and about two-thirds of the fajita seasoning. Set aside while you prep the veggies.
Prep the veggies: Slice peppers and onion into even strips. Toss with the remaining seasoning and a pinch of salt.
Sauté the cabbage: Heat a large skillet over medium-high.
Add 1 tablespoon olive oil. Add cabbage, salt, pepper, and cumin (if using). Cook 6–8 minutes, tossing often, until tender-crisp with a few golden edges.
Transfer to bowls or a platter and keep warm.
Cook the chicken: Return the skillet to medium-high. Add 1 tablespoon olive oil if the pan looks dry. Add chicken in a single layer.
Cook 5–7 minutes, flipping once, until browned and cooked through. Drizzle with lime juice and toss.
Cook peppers and onions: In the same skillet, add peppers and onions. Sauté 4–6 minutes until softened with some char on the edges but still a bit crisp.
If browned bits build up, splash in a tablespoon of water to deglaze.
Combine and taste: Add the chicken back to the skillet with the peppers and onions. Toss to coat and warm through. Taste and adjust salt, pepper, and lime.
Assemble bowls: Spoon a generous bed of cabbage into each bowl.
Top with the chicken-pepper mixture. Add any toppings you like—avocado, salsa, a dollop of yogurt, or a sprinkle of cheese.
Serve: Finish with fresh cilantro and extra lime wedges. Serve hot.