How to Make It
In a processor, pulse the garlic with the onion, lime juice, chili powder, salt and cumin. With the machine on, slowly drizzle in the olive oil until a wet paste forms. Rub the paste all over the steak.
Light a grill or preheat a grill pan. Grill the steak over a medium-high fire for 10 minutes, turning once, until an instant-read thermometer inserted in the thickest part registers 125° to 130° for medium rare. Transfer the steak to a cutting board and let rest for 5 minutes.
Cut the steak across the grain into 1/4-inch-thick slices. Arrange the meat on a platter. Squeeze 2 lime wedges over the steak slices, then top with the shredded cheese and cilantro. Serve with the warm corn tortillas and the remaining lime wedges.