1. In a large Dutch oven, add the stock, cabbage, mushrooms, carrots, rice vinegar, tamari, ginger, garlic, and chili garlic sauce. Bring to a boil, then turn the heat to medium-low and simmer for five minutes.
2. Whisk together the cornstarch and 1/4 cup of water. Stir into the soup. Simmer for a couple of minutes.
3. Add the noodles, and cook for a few more minutes. Stir in the tofu and most of the scallions.
4. Season to taste. If you want it more sour or hot, adjust accordingly.
5. Ladle into bowls and garnish with more scallions and hot sauce. Serve immediately.