Cut beef into thin slices and then marinating with marinating ingredients and cornstarch, except sesame oil. Set aside for at least 15 minutes. Mix in sesame oil just before frying.
Mix stir-frying sauce in a small bowl.
Heat the pan firstly and then add oil. When the oil becomes slightly hot, spread beef slices in. Let them stay for a while and do a quick fry until they turn pale.
Transfer the beef out and leave only 1 tablespoon of cooking oil in pan. Slow down the fire, place garlic and snow peas in. Fry for half minutes until just cooked.
Add beef slices back and stir in the stir fry sauce. Quickly fry until well mixed.