Remove stems from mushrooms. Make a light mushroom broth by simmering stems in 2 cups water for 10 minutes, then strain and reserve broth. Dice mushroom caps and set aside.
Put oil in a wok or wide skillet over medium heat. Add mushrooms, green onions, garlic, Sichuan peppercorns, red peppers. Sauté until aromatic, about 1 minute.
Add chili bean paste, soy sauce, mushroom broth, and tofu cook until heated through, about 3 to 5 minutes.
Add corn starch water, stir until thick.
Transfer cooked tofu to a serving dish, top with chopped peanuts.