Lunar New Year Dumplings

Name: Lunar New Year Dumplings
Ingredients: 2 cups all-purpose flour (about 8 1/2 ounces), plus more for dusting; 1/8 teaspoon kosher salt; 1/2 cup plus 1 tablespoon boiling water; Cornstarch, for dusting; 6 ounces napa cabbage, coarsely chopped (about 3 cups), plus whole cabbage leaves for lining steamer baskets; 6 ounces ground pork; 6 tablespoons scallions, finely chopped; 6 tablespoons chopped fresh Chinese chives or garlic chives, plus more for garnish; 2 tablespoons soy sauce; 1 1/2 teaspoons finely chopped garlic; 3/4 teaspoon fresh ginger, peeled and grated; 3/4 teaspoon toasted sesame oil; 1/2 cup soy sauce; 1/4 cup rice vinegar; 2 teaspoons thinly sliced scallions, white parts only; 1 teaspoon black pepper; 1/2 teaspoon toasted sesame seeds; Chile oil (optional)