In a mixing bowl, combine orange juice, lime juice, soy sauce, minced garlic, cumin, oregano, black pepper, and salt. Mix well.

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

Preheat the grill to high heat.

Remove the steak from the marinade and discard the marinade. Grill the steak for about 5 minutes on each side for medium-rare, or until desired doneness.

Let the steak rest for 5 minutes before slicing against the grain.

Serve the sliced carne asada with chopped cilantro, diced onion, sliced radishes, and lime wedges on the side.