Start by trimming any excess fat from the flank steak. Place it in a baking dish. For the marinade, mix olive oil, garlic, orange juice, lime juice, cumin, salt, and pepper in a bowl. Pour the marinade over the steak, ensuring it’s evenly coated. Cover with plastic wrap and refrigerate for at least 1 hour (but no more than 8 hours).
Preheat your grill or grill pan over medium-high heat. Brush the grates with a little oil to prevent sticking, then remove the steak from the marinade, shaking off any excess. Grill the steak for about 3-4 minutes on each side. For medium-rare, the internal temperature should reach 135°F. Once cooked, transfer the steak to a cutting board, cover with foil, and let it rest for 5 minutes. Resting helps the juices redistribute for tender, flavorful slices.
While the steak rests, heat your tortillas. Place them on the grill or in a dry skillet over medium-high heat for about 30 seconds per side until soft and slightly charred.
Using a sharp knife, slice the steak thinly against the grain to maximize tenderness. Prepare your tortillas by adding a few slices of steak, your favorite cheese, and any toppings like cilantro, red onion, or tomato. Serve immediately, and enjoy the burst of flavors in every bite.