Season the shrimp with cumin, chili powder, and garlic powder. Set aside.
Add two tablespoons of olive oil to a large skillet set over medium-high heat.
Add the bell peppers and red onion. Season with salt and black pepper, to taste, and stir to combine.
Cook, stirring occasionally until the vegetables soften and develop a bit of color, approximately 10 minutes. Transfer the onions and peppers to a plate.
Add the shrimp to the same skillet. Add a little more olive oil, if necessary. Season the shrimp with salt and black pepper, to taste, and cook just until the shrimp turns opaque approximately 3-4 minutes. Do not overcook. Remove from heat.
To serve, divide the rice between four serving bowls and top each bowl with the cooked vegetables and shrimp. Garnish with additional cilantro and lime wedges, if desired.