In a bowl, combine olive oil, minced garlic, lime juice, cumin, chili powder, salt, and pepper to create a rich marinade. Rub this mixture generously onto the skirt steak, ensuring it's well-coated. Cover and let marinate for at least 30 minutes—ideally overnight in the refrigerator—to maximize the flavor infusion.

Preheat your grill or a cast-iron skillet over medium-high heat until it reaches about 400°F.

Place the marinated skirt steak on the hot grill or skillet. Cook for 3-5 minutes on each side until it reaches medium-rare doneness (about 135°F). Let it rest for 5 minutes.

Carefully slice the skirt steak against the grain into thin strips.

Warm the tortillas on the grill for about 30 seconds on each side or in a skillet until pliable.

Grab a warm tortilla, layer on sliced skirt steak, add chopped onions and cilantro, then top with salsa and a squeeze of lime.