Marinate the steak by blending olive oil, minced garlic, ground cumin, chili powder, salt, and pepper in a bowl. Coat the flank steak thoroughly and let it marinate for at least 30 minutes.

In a medium saucepan, bring water to a boil. Stir in your choice of rice, then cover and reduce heat to low. Simmer for 18-20 minutes until the rice is tender.

Preheat your grill to medium-high heat. Grill the marinated flank steak for 4-5 minutes on each side until medium-rare. Let it rest for 5 minutes before slicing.

In a large mixing bowl, combine cooked rice, black beans, corn, diced tomatoes, chopped onion, cilantro, and lime juice, and toss gently.

Assemble your bowl by dividing the rice and bean mixture into serving bowls, topping with sliced grilled steak, avocado, shredded cheese, and sour cream or salsa.