Combine cumin, chili powder, garlic powder, smoked paprika, onion powder, and red pepper flakes in a small bowl and mix well. For deeper flavor, toast the spices in a dry skillet over medium heat for about 30 seconds before mixing.

Slice the steak thinly against the grain into about 1/4-inch pieces, then season generously with salt, black pepper, and the spice blend.

Heat a large skillet or cast-iron pan over high heat for about 2 minutes until very hot.

Add the olive oil, then add the steak in a single layer and cook for 2 to 3 minutes without stirring to form a crust. Flip and cook for 1 to 2 minutes more, until browned and cooked to medium-rare, about 130 to 135°F (54 to 57°C).

Warm the flour tortillas for about 30 seconds in the microwave wrapped in a damp kitchen towel, or heat them briefly over a gas flame so they stay soft and pliable.

Arrange the cooked rice, black beans, cheese, bell peppers, onion, corn, cilantro, and salsa in separate piles so assembly is easy.

Lay one warm tortilla flat and layer rice first, then steak, beans, cheese, and your preferred toppings in the center third of the tortilla.

Fold the bottom edge over the filling, fold in the sides, and roll tightly upward to seal the burrito. Repeat with the remaining tortillas.