- 2 cans (14.5 ounces each) reduced-sodium chicken broth
- 2 tablespoons soy sauce
- 1/4 to 1/2 teaspoon crushed red pepper
- 8 ounces fresh shiitake mushrooms (about 4 cups), stemmed, caps thinly sliced
- 3 to 4 tablespoons rice vinegar
- 2 tablespoons cornstarch
- 1 large egg, lightly beaten
- 1/2 package (7 ounces) soft or firm tofu, cut into 1/4-inch cubes, drained
- 2 tablespoons finely grated fresh ginger
- 3 scallions, thinly sliced
In a large (5-quart) pot, combine broth, soy sauce, crushed red pepper, and 2 cups water. Bring to a boil over medium heat. Add mushrooms; reduce heat, and simmer until tender, about 10 minutes.
In a small bowl, whisk together 3 tablespoons vinegar and cornstarch. Add to pot; simmer, stirring, until soup is thickened, about 1 minute.
Add egg through a slotted spoon, and stir to form ribbons. Stir in tofu. Remove from heat; let stand, covered, 1 minute. Put ginger in a small sieve, and squeeze to release juice into soup (discard solids). Taste; add remaining tablespoon vinegar, if desired. Serve sprinkled with scallions.