Step 1

Adjust oven rack 8 inches from broiler element and heat broiler. Combine beans and 1 tablespoon vegetable oil in bowl and toss to coat. Spread on rimmed baking sheet (do not wash bowl). Broil beans until softened and charred in places, 10 to 15 minutes, flipping beans halfway through broiling. Return beans to bowl, add salt, and toss to distribute evenly. Cover with plate. Stir Shaoxing wine, soy sauce, and sugar in small bowl until sugar is dissolved, and set aside.

Step 2

Combine remaining 1½ tablespoons vegetable oil, chiles, and Sichuan peppercorns in wok and cook over medium-low heat until fragrant, about 1 minute. Add garlic and ginger and cook, stirring constantly, until fragrant, about 1 minute. Add pork and mash and smear until pork and garlic mixture are evenly combined. Increase heat to medium-high and continue to cook, chopping meat into ¼-inch chunks with edge of spatula until cooked through, about 2 minutes.

Step 3

Add beans and ya cai and toss to combine. Add Shaoxing wine mixture and cook, stirring constantly, until no liquid remains in wok, 1 to 2 minutes. Transfer to serving platter, drizzle with sesame oil, and serve.