• Place the flank steak in a large resealable plastic bag. In a small bowl, mix together the olive oil, minced garlic, salt, and pepper. Pour the marinade over the steak in the bag, seal it, and let it marinate in the refrigerator for 1 to 6 hours.
• Preheat your grill to medium heat. Remove the steak from the marinade, gently patting off the excess with a paper towel. Grill the steak for about 8 minutes on each side, or until it reaches an internal temperature of 160°F. Once cooked, allow the steak to rest for 5 minutes before slicing it thinly against the grain.
• Meanwhile, slice the lettuce into strips, and thinly slice the tomatoes, avocado, and red onion.

To serve, you have two options:

• Arrange the sliced steak, lettuce, tomatoes, avocado, and onion on a tray so everyone can assemble their wraps as they like.
• Alternatively, prepare each wrap by placing a tortilla flat, adding a layer of sliced steak, followed by lettuce, avocado, onion, and tomato. Roll up the tortilla and serve immediately.