3/4 pound flank or tri-tip steak, sliced across the grain into 1/4 inch slices
vegetable oil for deep frying
2 ounces dried bean thread noodles
1 leek, white part only, halved lengthwise and cut into 2 inch lengths
5 green onions, trimmed and cut into 2 inch lengths
For the marinade:
2 tablespoons water
1 tablespoon soy sauce
1 tablespoon vegetable oil
1 teaspoon minced ginger
2 teaspoons cornstarch
For the sauce:
2 tablespoons soy sauce
2 tablespoons sugar
2 teaspoons chinese rice wine or dry sherry
1 1/2 teaspoons chinese black vinegar or balsamic vinegar
1 teaspoon hoisin sauce
1 teaspoon chili bean sauce or chili garlic sauce
Marinate the beef: stir the water, soy sauce, oil, ginger, and cornstarch together in a medium bowl until the cornstarch is dissolved. Cut the slices of beef into 2 inch pieces and toss them in the marinade to coat. Let stand for 20 minutes.
Prepare the sauce: stir the soy sauce, sugar, rice wine, black vinegar, hoisin sauce and chili bean sauce together in a bowl.
Pour enough oil into a wide deep skillet to come to depth of 3 inches. Pull the bean thread noodles gently apart to loosen the strands. Slip the noodles into the oil and fry just until they puff and expand, about 5 seconds; turn the noodles in the oil if necessary so they all puff evenly. Scoop the noodles from the oil with a slotted spoon and drain on paper towels then arrange the noodles on a serving platter and set aside. Reserve the oil.
Heat a wok over high heat until hot. Add 1 tablespoon of the reserved oil and swirl to coat the sides. Scatter the steak slices into the work and stir-fry just until barely pink in the center, 1 to 2 minutes. Scoop the beef onto a plate and set aside.
Add the green onions and leek to the wok and stir-fry until wilted, about 30 seconds. Pour ino the sauce and return the beef to the wok. Cook until the beef is heated through and coated evenly with sauce, 1 to 2 minutes. Spoon the beef and sauce over the noodles and serve.