In a medium bowl or large zip-lock bag, combine the beef, pear, soy sauce, garlic, ginger and onions. Refrigerate for at least an hour, or overnight.
Heat a drizzle of oil in a large skillet set over medium-high heat, remove the beef from the marinade and stir-fry, tossing with tongs, just until cooked through. If you like, chop the meat into smaller pieces to make it easier to wrap.
Serve with soft lettuce leaves to fill, top with green onion and sesame seeds, wrap and eat.
Total time: 15 min (plus marinating time)