Preheat your oven to 375°F (190°C). Carefully cut the tops off each large poblano pepper and remove the seeds and veins. Place the peppers cut side up on a parchment-lined baking sheet. Roast them in the oven for about 12-15 minutes, until they start to soften and become fragrant.

While the peppers are roasting, heat a skillet over medium heat and add the ground beef. Cook until browned, breaking it apart with a spoon, about 5-7 minutes. Midway through, add the diced onion and sauté until translucent, around 3-4 minutes. Drain any excess grease before adding minced garlic, chili powder, and cumin. Stir for an additional minute.

Stir in the cooked white rice, corn, black beans, and fire-roasted diced tomatoes to the skillet. Let the mixture simmer on low, allowing flavors to meld. Season with kosher salt and pepper to taste. Fold in 1 cup of shredded cheese and chopped cilantro.

Remove the softened poblano peppers from the oven and fill each with the flavorful filling. Sprinkle the remaining cheese on top. Return to the oven and bake for an additional 10-15 minutes, until the cheese is melted and bubbly.

Once baked, let the stuffed poblano peppers rest for a few minutes. Garnish with chopped cilantro before serving.