Ingredients:

• 1 (4 pound) whole chicken
• 15 cups cold water
• 1 medium yellow onion, halved
• 3 cloves garlic, smashed
• 3 scallions, halved crosswise
• 1-inch fresh ginger, cut into 1/4-inch coins and smashed
• 1 tablespoon Tianjin preserved vegetables, finely chopped (optional)
• Kosher salt, for seasoning the broth to taste
• 1 pound ground pork
• 2 scallions, minced
• 1 clove garlic, minced
• 1/4-inch fresh ginger, peeled and minced
• 1 large egg
• 1 tablespoon Shaoxing wine
• 3 tablespoons water
• 1 tablespoon toasted sesame oil
• 1 1/2 teaspoons cornstarch
• 1 teaspoon sugar
• 1 teaspoon kosher salt
• 1/8 teaspoon freshly ground black pepper
• All-purpose flour, for dusting the sheet pan (optional)
• 80 square wonton wrappers
• 1 scallion, thinly sliced
• 1 tablespoon toasted sesame oil