In a medium bowl, whisk together lime juice, olive oil, chopped cilantro, minced garlic, ground cumin, chili powder, salt, and black pepper until well combined.

Place the flank steak in a resealable plastic bag or shallow dish and pour the marinade over it. Seal and refrigerate for at least 30 minutes.

Prepare rice according to package instructions, which usually takes about 20 minutes.

In a small saucepan, heat the canned black beans over medium heat for about 5 minutes.

If using fresh corn, cook it in boiling water for about 5-7 minutes; if using frozen corn, heat until warmed.

Preheat your grill to medium-high heat. Grill the marinated flank steak for 4-5 minutes on each side.

Let the steak rest for 5-10 minutes, then slice it thinly against the grain.

In serving bowls, layer the rice, black beans, corn, sliced steak, cherry tomatoes, avocado, red onion, and optional feta cheese.

Garnish with extra cilantro and serve with lime wedges.