In a mixing bowl, combine olive oil, lime juice, orange juice, minced garlic, cumin, chili powder, salt, black pepper, and cilantro to create the marinade.

Place the flank steak in a resealable bag or shallow dish and pour the marinade over it. Seal the bag or cover the dish and refrigerate for at least 1 hour, preferably overnight.

Preheat the grill to medium-high heat.

Remove the steak from the marinade and let excess marinade drip off. Discard the marinade.

Grill the steak for about 5-7 minutes on each side for medium-rare, or until desired doneness.

Remove from the grill and let rest for 5 minutes before slicing against the grain.

Serve the carne asada with diced onion, chopped cilantro, salsa, and avocado on the side. Enjoy in tacos or as a main dish.