Heat a wok over high heat for 30 seconds. Add 1/2 cup oil and swirl around wok. Add 1/2 teaspoon each ginger and garlic and the beef mix; stir−fry for 2 to 3 minutes.
Remove from wok, draining oil. Put 2 tablespoons oil in wok and heat. Stir−fry remaining 1/2 teaspoon garlic and ginger until brown.
Add reserved beef mix, bamboo shoots, mushrooms and wine. Stir−fry over high heat for 1 minute.
Add soy sauce, chicken stock, salt and pepper.
Thicken with reserved cornstarch mix, stirring gently.
Pour into serving dish, and garnish with shredded scallion