Preheat your Oven to 425°F. Line a large rimmed Baking Sheet with Aluminum Foil or Parchment Paper for easy cleanup. In a small Mixing Bowl, combine the 1 ½ tsp chili powder, 1 tsp ground cumin, ½ tsp smoked paprika, ½ tsp garlic powder, ½ tsp onion powder, ¼ tsp cayenne pepper (if using), 1 tsp fine sea salt, and ¼ tsp black pepper freshly ground. Stir to mix the seasoning blend.

In a large Mixing Bowl, combine the sliced 1 ½ lb boneless skinless chicken breasts sliced into ½-inch strips, 3 whole bell peppers mixed colors (red, yellow, green), seeded and sliced into strips, and 1 large yellow onion halved and sliced into half-moons. Drizzle with 3 tbsp extra-virgin olive oil and 2 tbsp fresh lime juice from about 1 lime, then sprinkle the seasoning blend over everything. Toss well until the 1 ½ lb boneless skinless chicken breasts sliced into ½-inch strips and vegetables are evenly coated.

Spread the 1 ½ lb boneless skinless chicken breasts sliced into ½-inch strips and vegetable mixture in a single, even layer on the prepared Baking Sheet — avoid overcrowding so everything roasts rather than steams. Roast in the preheated Oven for 20–25 minutes, until the 1 ½ lb boneless skinless chicken breasts sliced into ½-inch strips is cooked through (internal temp 165°F) and the 3 whole bell peppers mixed colors (red, yellow, green), seeded and sliced into strips and 1 large yellow onion halved and sliced into half-moons are tender with lightly charred edges.

Rinse peppers under cold water and pat dry. Slice off tops and bottoms, stand upright, and cut down along the inside to remove seeds and white ribs. Slice lengthwise into ½-inch strips; halve crosswise for shorter pieces. Keep sizes uniform so everything cooks evenly. If adding onion, slice it now. Measure out olive oil, salt, and pepper. Have everything ready before the pan goes on — sautéing moves fast.