How to Make It
In a small bowl, cover the mushrooms with boiling water and let stand until softened, about 30 minutes. Drain and coarsely chop the mushrooms; discard the soaking water.
In a large saucepan, heat the canola oil. Add the pork, garlic, ginger and scallions and cook over moderately high heat, stirring occasionally, until the pork is golden brown, about 3 minutes. Stir in the stock and add the tofu, 1/3 cup of vinegar, the soy sauce, sugar, pepper, sesame oil, mushrooms and 1 tablespoon of Sriracha. Bring the soup to a simmer and season with salt. While stirring constantly, drizzle in the eggs and cook until strands form, 1 minute. Serve hot, passing rice vinegar and Sriracha at the table.