In a bowl, mix together olive oil, minced garlic, ground cumin, chili powder, salt, and pepper. Rub this mixture evenly over the flank steak and let it marinate for at least 30 minutes, or overnight for deeper flavor.

In a saucepan, bring water to a boil. Add the rice, cover, and reduce the heat to low to simmer for 18–20 minutes until tender and fluffy. Fluff it with a fork when done.

Preheat your grill to medium-high. Grill the marinated steak for about 4–5 minutes per side, depending on your desired level of doneness. After grilling, let the steak rest for 5 minutes before slicing.

In a large bowl, mix together the cooked rice, black beans, corn, diced tomatoes, red onion, cilantro, and lime juice. Toss gently to combine all flavors.

Cut the rested steak thinly against the grain. Layer the sliced steak over the rice and bean mixture in each serving bowl.

Finish each bowl with avocado slices, shredded cheese, and a dollop of sour cream or salsa. Serve warm and enjoy immediately!