Step 1

Put 2 cups cold water and the dried shiitake mushrooms in a small pot and bring to a boil. Turn off the heat and let sit to rehydrate for 30 minutes.

Step 2

Squeeze excess water from the mushrooms, cut off and discard the stems and finely chop the mushrooms. Measure the mushroom-soaking liquid and add enough cold water to come to 1 1/2 cups.

Step 3

Mix the cornstarch and 2 tablespoons cold water in a small bowl until combined; set aside.

Step 4

Heat 2 tablespoons of the vegetable oil in a wok or large high-sided skillet over medium-high heat until it starts to smoke. Add the shiitakes and cook until browned, about 4 minutes. Lower the heat to medium, add the remaining 2 tablespoons vegetable oil, the ginger, douchi, doubanjiang, Sichuan peppercorn powder, garlic and dried chile, if using, and cook until everything is bright red, about 1 minute.

Step 5

Add the mushroom-soaking liquid to the wok, scraping any brown bits off the bottom. Gently stir in the tofu and bring to a boil. Add the soy sauce and sugar, then stir in the cornstarch slurry and half of the scallions. Bring to a simmer and simmer until the sauce is glossy, about 1 minute.

Step 6

Transfer to a serving dish, sprinkle with the remaining scallions and more Sichuan peppercorn powder if desired and drizzle the toasted sesame oil on top.