In a small bowl, whisk together the chili powder, cumin, garlic powder, sea salt, and black pepper.
Toss the shrimp with half of the spice blend and the lime juice until evenly coated.
Heat the olive oil in a large skillet over medium-high heat.
Add the sliced bell peppers and red onion to the skillet, sautéing for 5-6 minutes until tender-crisp and slightly charred.
Remove the vegetables from the skillet and set them aside on a plate.
In the same skillet, add the shrimp in a single layer and cook for 2-3 minutes per side until pink and opaque.
Warm the cooked brown rice and black beans in a separate pot or microwave until heated through.
Assemble the bowl by layering the rice and beans at the bottom, then topping with the sautéed vegetables and shrimp.
Garnish with fresh avocado slices and chopped cilantro before serving.