Grind ½ teaspoon Sichuan peppercorns using mortar and pestle until finely ground; transfer to medium bowl.

Whisk in ⅓ cup unsweetened natural peanut butter and ⅓ cup soy sauce until fully incorporated.

Whisk in 3 tablespoons Chinese black vinegar until combined. Add ¼ cup chili crisp, 2 tablespoons sugar, 2 minced garlic cloves, and 1 teaspoon grated fresh ginger and whisk to combine; set aside. (Sauce should be thick enough to coat a spoon; add 1 to 2 tablespoons water to thin out sauce if needed. Sauce can be refrigerated for up to 1 week.)

Bring 4 quarts water to boil in large pot.

Meanwhile, heat 1 tablespoon vegetable oil in 12-inch nonstick skillet over medium-high heat until shimmering. Add 8 ounces ground pork and cook until browned, breaking up meat into small pieces, 5 to 7 minutes.

Add thinly sliced bok choy stalks and thinly sliced scallion whites and cook, stirring constantly, for 1 minute.

Stir in coarsely chopped bok choy greens, 2 tablespoons Shaoxing wine, 2 tablespoons soy sauce, and ½ teaspoon sugar, stirring to coat pork and bok choy. Reduce heat to medium and cook until bok choy greens are wilted, about 1 minute. Remove from heat.

Add 1 pound fresh Chinese wheat noodles to now-boiling water; reduce heat to maintain very gentle simmer; and cook, stirring occasionally, until almost tender (center of noodles should be firm with slightly opaque dot), 3 to 5 minutes.

Drain noodles very well in colander and rinse with running water. Drain well.

Transfer noodles to bowl with ¾ cup sauce, tossing to coat.

To serve, divide noodles among individual serving bowls. Top with pork mixture, then sprinkle with scallion greens. Serve with remaining chili crisp sauce and extra chili crisp, mixing each bowl well before eating.