Mix together 1 tbsp of the soy sauce, the salt, sherry and 2 tbsps of the oil. Add the lamb slices and leave to marinate for 5 minutes. Mix the remaining soy sauce with the vinegar, sesame seed oil and pepper in a small bowl.
Heat the remaining oil in the pan. Add the garlic and stir fry for 10 seconds. Add the meat and stir fry until browned.
Shred a few of the scallions and set aside for garnish. Cut the remainder into 2 inch pieces and add to the meat together with the vinegar mixture. Stir-fry for a few seconds. Serve hot, garnished with the reserved scallions.
Note: Beef may be substituted for lamb, if preferred.