Hot and Sour Soup

1 cup sliced fresh mushrooms or 4 dried black Chinese mushrooms
1 can (15 oz.) fat-free, reduced-sodium chicken or vegetable broth
1 tsp. minced fresh ginger root, peeled
2 scallions, chopped
1 cup finely chopped bok choy cabbage
1/2 can (8 oz.) bamboo shoots
1-2 tsp. hot pepper oil or sauce, or to taste
1 Tbsp. rice wine vinegar
1 tsp. "lite" soy sauce
1/2 cup extra firm tofu, slivered (about 3 oz.)
1 Tbsp. cornstarch, dissolved in 1/4 cup cold water
1 egg white (optional)



If using dried mushrooms, soak in hot water to cover about 15 minutes. Drain, remove stems and slice. In large saucepan, bring broth to boil. Reduce heat to simmer and add ginger, scallions, cabbage and bamboo shoots. Cook for 3 minutes. Add pepper oil, vinegar, soy sauce, tofu and mushrooms. Simmer 3 minutes more. If thicker consistency is desired, strain soup into another saucepan to separate broth and set solid contents aside. Set broth over medium heat and slowly pour in cornstarch mixture while stirring, until soup thickens. If desired, add egg white while stirring to form long strands, then add reserved ingredients. Serve immediately.