Marinate and grill flank steak (see Grilled Flank Steak Recipe).
While steak is marinating, prepare desired toppings.
Once steak is cooked and has rested, slice it into ¼-½ inch slices across the grain, and at a 45° angle from top to bottom. Cut larger strips in half if desired (or they can be folded when added to the tacos).
On a gas stovetop or electric burner, heat and brown tortillas. Using metal tongs, flip each tortilla a couple of times to brown and heat through.
Add steak & toppings to the warm tortillas, squeeze with a lime wedge and enjoy!
Notes
*Can use flour tortillas in place of corn tortillas.