In a mixing bowl, combine olive oil, lime juice, orange juice, minced garlic, cumin, chili powder, salt, black pepper, and oregano. Mix well.

Place the flank steak in a resealable bag or shallow dish and pour the marinade over it. Seal or cover and refrigerate for at least 30 minutes, preferably 2 hours.

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 is reached.

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

Serve the sliced carne asada in warmed corn tortillas, topped with chopped cilantro, diced onion, and sliced radishes. Squeeze lime juice over the top.