In a mixing bowl, whisk together olive oil, lime juice, cumin, garlic powder, oregano, salt, black pepper, and chili powder.

Place the flank steak in a large resealable plastic bag and pour the marinade over it. Seal the bag and refrigerate for at least 30 minutes, or up to 4 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.

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

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