In a small bowl combine lamb with baking soda and 1/4 cup cold water. Mix well and soak 5 hours.
Rinse lamb slices and dry well on paper towels. In a small bowl mix together egg white, salt, cornstarch, 1 teaspoon of the garlic, peanut oil, and 1 tablespoon of the Shao Hsing. Add lamb and toss to coat with marinade.
In another small bowl combine brown bean sauce, remaining 3 tablespoons Shao Hsing, sugar, monosodium glutamate, stock, vinegar and sesame oil. In a cup mix cornstarch with a little cold water to consistency of heavy cream and whisk into bean sauce. Set aside.
In first wok heat 4 cups oil over high heat to 375 degrees. Drain lamb, pat dry and deep-fry 1 minute, turning pieces several times with a metal spoon. Use a slotted spoon to remove lamb to paper towels. Return lamb to oil and deep-fry 1 minute more; remove and drain again. Return lamb a third time and deep-fry 30 seconds more; remove and drain on clean paper towels.
In second wok heat remaining 1 tablespoon oil over high heat. Add leek, remaining garlic and chili peppers to taste; stir-fry 30 seconds. Add mushrooms and lamb and mix well. Stir reserved bean sauce mixture and add to wok, tossing to combine. Bring liquids to a boil and remove from heat as soon as sauce begins to thicken. Serve immediately with rice.