7 oz firm tofu
4 tablespoons soy sauce
1 teaspoon toasted sesame seed oil
3 tablespoons plus 1 ½ teaspoon cornstarch
1 boneless center-cut pork chop (1/2 inch thick, about 6 oz.) trimmed of fat and cut into 1 inch by 1/8 inch matchsticks
3 tablespoons plus 1 teaspoon cool water
1 large egg
6 cups low sodium chicken broth
1 cup bamboo shoots (from one 5 oz can), sliced lengthwise into 1/8 inch strips
4 oz fresh shiitake mushrooms, stems removed, caps sliced ¼ inch thick (about a cup)
5 tablespoons Chinese black vinegar or 1 tablespoon red wine vinegar plus 1 tablespoon balsamic vinegar
2 teaspoons chili oil (optional)
1 teaspoon ground white pepper
3 medium scallions, sliced thin
Place tofu in pie plate and set heavy plate on top. Weigh with 2 cans; let stand at least 15 minutes (tofu should release about ½ cup liquid).
Whisk 1 tablespoon soy sauce, sesame seed oil and 1 teaspoon cornstarch in medium bowl; toss with pork and set aside for 10-30 minutes.
Combine 3 tablespoons cornstarch with 3 tablespoons water in a small bowl and mix thoroughly; set aside, leaving spoon in bowl.
Mix remaining ½ teaspoon cornstarch with remaining 1 teaspoon water in remaining bowl; add egg and beat with fork until combined. Set aside.
Bring broth to boil in large sauce pan set over medium high heat. Reduce to medium low; add bamboo shoots and mushrooms and simmer until mushrooms are just tender, about five minutes.
While broth simmers, dice tofu into half inch cubes. Add tofu and pork with marinade to soup, stirring to separate any pieces that stick together. Continue to simmer until pork is no longer pink, about two minutes.
Stir cornstarch mixture to recombine. Add to soup and increase heat to medium high; cook stirring occasionally, until soup thickens and turns translucent, about one minute.
Stir in vinegar, chili oil, pepper, and remaining 3 tablespoons soy sauce; turn off heat.
Without stirring soup, use spoon to drizzle very thin streams of egg mixture into pot in circular motion.
Let soup sit one minute, then return saucepan to medium high heat. Bring to gentle boil, then immediately remove from heat.
Gently stir soup to evenly distribute egg. Ladle into bowls and top with scallions.