In a small microwave-safe bowl, mix the black beans, corn, cumin, and garlic powder; heat on high for 60 to 90 seconds until hot.
Warm the tortillas in a large dry skillet over medium heat for 30 seconds per side or microwave for 15 seconds to ensure flexibility.
Place the tortillas on a flat surface and distribute the precooked rice evenly in the center of each.
Spoon the seasoned bean and corn mixture over the rice layer.
Top with avocado slices, shredded lettuce, salsa, and fresh cilantro.
Fold the left and right sides of the tortilla toward the center, then roll tightly from the bottom upward to seal the burrito.