In a bowl, mix olive oil, lime juice, minced garlic, cumin, chili powder, salt, and black pepper. Add the flank steak and marinate for at least 30 minutes, or up to 2 hours in the refrigerator.

Grill the Steak

Preheat your grill to medium-high heat. Remove the steak from the marinade and grill for about 4-5 minutes on each side, or until it reaches your desired doneness. Let it rest for 5 minutes before slicing.

Prepare the Toppings

While the steak is resting, prepare the toppings by chopping the cilantro, dicing the onion and tomato, slicing the avocado, and slicing the radishes.

Warm the Tortillas

Heat the corn tortillas on the grill for about 30 seconds on each side until warm and pliable.

Assemble the Tacos

Slice the grilled steak against the grain into thin strips. Place some strips on each tortilla and top with cilantro, onion, tomato, avocado, radishes, and a dollop of sour cream.

Serve

Serve the tacos immediately with lime wedges on the side.