How to Make It
Heat a large saucepan over medium-high. Add pork, and cook, stirring occasionally to crumble, until browned, 4 to 5 minutes. Add mushrooms; cook, stirring occasionally, until slightly softened, 1 to 2 minutes. Add tomato paste; cook, stirring constantly and scraping browned bits from bottom of saucepan, 1 minute. Stir in stock, soy sauce, and vinegar. Increase heat to high, and bring to a boil.
Whisk together water and cornstarch, and stir into pork mixture. Return to a boil, and boil until slightly thickened, 3 to 4 minutes. Add eggs boiling mixture, and gently stir. Immediately remove soup from heat. Stir in bamboo shoots, tofu, scallions, sesame oil, and pepper.