In a large skillet, heat the olive oil over medium-high heat. Add the sliced flank steak and season with salt, pepper, chili powder, and cumin. Cook for about 3-4 minutes until browned. Remove the steak from the skillet and set aside.
In the same skillet, add the diced onion and bell pepper. Sauté for about 5 minutes until the vegetables are tender. Add the minced garlic and cook for an additional minute.
Return the cooked steak to the skillet and add the cooked rice. Stir everything together and cook for 2-3 minutes until heated through.
Sprinkle the shredded cheddar cheese over the top of the mixture. Cover the skillet and let it sit for 2-3 minutes until the cheese is melted.
Remove from heat and garnish with chopped cilantro, if desired. Serve with lime wedges on the side.