1. Place the steak in the freezer for 1 hour.
2. Meanwhile, prepare the marinade. Toast sesame seeds in a small skillet over medium heat. Watch carefully, as they go from barely toasted to burnt very quickly. Remove from heat just as they just begin to turn golden, about 3 to 4 minutes. Set aside.
3. In a blender or food processor, combine pear, garlic, soy sauce, wine, sesame oil, honey, sugar, and pepper and blend into a coarse mixture. Place mixture in a resealable plastic bag. Add toasted sesame seeds and onion and massage bag gently to combine the ingredients.
4. Slice the partially frozen steak across the grain into very thin slices. If steaks are large, it may be easier to cut them in half with the grain, then slice thinly against the grain. Add slices to the marinade in the plasticbag, and massage the bag to distribute the marinade evenly over the meat. Refrigerate for at least 4 hours and up to 24 hours.
5. When ready to cook, adjust oven rack so that it is 4 inches from the heating element. Preheat the broiler to high (about 550 degrees).Line a baking sheet with foil. Spread the meat, onions, and marinade in a single layer on the baking sheet. Broil 5 minutes, then turn the meat and broil second side about 3 minutes. The meat should be cooked throughand slightly caramelized in spots. While meat cooks, wash lettuce leaves and pat dry.
6. To serve, divide beef among the lettuce leaves, sprinkle with scallions, then roll up the meat in the lettuce leaves.
Source: Hannaford fresh Magazine, January - February 2012