In a small bowl, whisk together the olive oil, chopped cilantro, lime juice, minced garlic, cumin, salt, and pepper.
Place the flank steak in a shallow dish or resealable bag and pour half of the marinade over the meat.
Allow the steak to marinate for at least 30 minutes in the refrigerator.
Heat a cast-iron skillet or outdoor grill to medium-high heat.
Cook the steak for 4 to 6 minutes per side, or until the internal temperature reaches 135°F for medium-rare.
Remove the steak from the heat and let it rest on a cutting board for 10 minutes.
While the steak rests, fold the remaining half of the cilantro-lime marinade into the warm cooked rice.
Slice the steak thinly against the grain into bite-sized strips.
Distribute the cilantro-lime rice, black beans, corn, and diced red onion equally among four bowls.
Top each bowl with the sliced steak and garnish with additional lime wedges if desired.