Whisk together cornstarch and water; set aside.
In a stock pot, warm chicken stock over medium heat. When stock begins to steam, add bamboo shoots, water chestnuts and shiitake mushrooms; cook 15 minutes, adjusting heat if necessary to keep soup just below a boil.
Stir in white pepper, vinegar, salt and hot pepper to taste. Add cornstarch mixture slowly, stirring until mixture is thick and well-combined (at least 2 minutes - taste to make sure there is no lingering cornstarch aftertaste before proceeding). Add beaten egg, stirring to make swirls of cooked egg in the soup, with tofu pieces and sesame oil.
Serve immediately.Makes 8 Source: