Preheat your oven to 375°F (190°C).

In a medium saucepan, combine the brown rice and vegetable broth. Bring to a boil, then reduce heat to low, cover, and simmer for about 45 minutes, or until the rice is tender and the liquid is absorbed.

While the rice cooks, heat a large skillet over medium heat. Add a splash of oil and sauté the diced onion and bell peppers until softened, about 5-7 minutes. Add the minced garlic and cook for an additional 1-2 minutes until fragrant.

Stir in the black beans, diced tomatoes (with their juice), corn, cumin, chili powder, smoked paprika, salt, and pepper. Cook for about 5-10 minutes until everything is heated through.

Once the rice is cooked, add it to the skillet with the vegetable mixture. Stir until well combined.

Transfer the rice and vegetable mixture into a greased 9x13-inch baking dish. Spread it out evenly.

Sprinkle the shredded cheese on top of the casserole.

Bake in the preheated oven for 20-25 minutes, or until the cheese is melted and bubbly.

Remove from the oven and let it cool for a few minutes. Garnish with fresh cilantro.

Serve warm with avocado slices and lime wedges on the side.