Rinse beef, shred it thinly. Marinate with soy sauce and cornstarch for 10 minutes. Rinse water chestnuts. Peel and dice. Mix well with the salt, sugar, soy sauce, dark vinegar, pepper powder, and sesame oil. Heat oil in a wok till hot. Quickly stir-fry the beef shreds till the beef turns white. Remove and drain. Save some of the oil in the wok. Stir fry spring onions, ginger and garlic for a few seconds. Add the diced water chestnuts and Chili Nam Yuey. Stir fry for a few seconds. Add the shredded beef. Mix well. Pour in the seasoning. Stir till pasty. Remove and serve. From The Chinese Regional Cuisine Series, Szechuan Cooking.