Preheat your oven to 425°F and line a large sheet pan with parchment paper for easy cleanup.
Slice the chicken breast into thin strips and place them on the pan along with the sliced bell peppers and red onion.
Drizzle the avocado oil over the chicken and vegetables, then sprinkle with chili powder, cumin, garlic powder, sea salt, and black pepper.
Toss everything thoroughly with your hands or tongs to ensure an even coating of oil and spices, then spread into a single layer.
Roast for 15 to 18 minutes until the chicken is golden and cooked through and the vegetables are tender with slightly charred edges.
While the pan is in the oven, warm your pre-cooked brown rice in a small pot or microwave.
Divide the warm rice into a bowl and top with the hot chicken and vegetable mixture.
Finish the bowl with fresh avocado slices, chopped cilantro, and a bright squeeze of lime juice before serving.