In a large mixing bowl, stir together 1 1/2 cups of the flour and the yeast. In a small saucepan, heat and stir milk, sugar, butter, and salt just until warm (120 degrees F to 130 degrees F) and butter almost melts. Add to flour mixture; add one of the eggs. Beat with an electric mixer on low to medium speed for 30 seconds, scraping side of bowl constantly. Beat on high speed for 3 minutes. Using a wooden spoon, stir in as much of the remaining flour as you can.

Turn dough out onto a lightly floured surface. Knead in enough of the remaining flour to make a moderately soft dough that is smooth and elastic (3 to 5 minutes total). Shape dough into a ball. Place dough in a lightly greased bowl, turning once to grease surface. Cover and let rise in a warm place until double (about 1 hour).

Prepare Pork-and-Cabbage Filling. Set the filling aside to cool.

Punch dough down. Turn dough out onto a lightly floured surface. Divide dough into 15 pieces. Gently pull each piece into a ball, tucking edges under to make smooth tops. Cover and let rest for 10 minutes.

Preheat oven to 350 degrees F. Line an extra-large baking sheet with foil; grease foil. Roll or pat each ball of dough into a 4-inch circle. Brush edges with a little water. Place 2 tablespoons filling in center of each circle. Bring up edges of dough around filling, stretching dough just until edges meet; pinch to seal. Place buns seam side down on prepared baking sheet.

In small bowl, combine remaining egg and the 1 tablespoon water. Brush evenly over buns. If desired, sprinkle with sesame seeds.

Bake for 15 to 18 minutes or until buns are golden brown. Transfer buns to a wire rack; cool slightly. Serve warm. If desired, garnish the platter with bok choy leaves. Makes 15 buns.

Pork-and-Cabbage Filling: In a small bowl, stir together 2 tablespoons soy sauce, 1 teaspoon cornstarch, 1 teaspoon sugar, 1/2 teaspoon toasted sesame oil, and 1/4 teaspoon ground black pepper; set aside. In a large skillet, cook and stir 1 teaspoon grated fresh ginger and 1 clove garlic, minced, in 1 tablespoon hot butter for 15 seconds. Add 3 cups finely shredded baby bok choy or Chinese cabbage, 1 cup chopped fresh shiitake mushrooms, 3/4 cup shredded carrot, and 1/2 cup thinly sliced green onion. Cook and stir for 2 minutes. Remove mixture from skillet. Heat 1 tablespoon butter in skillet; add 8 ounces chopped lean boneless pork. Cook and stir about 2 minutes or until pork is no longer pink. Return vegetable mixture to skillet. Add soy sauce mixture. Cook and stir for 2 minutes.

Make-Ahead Tip: Prepare and bake buns as directed; cool completely. Place in an airtight container and freeze for up to 3 months. Thaw buns, covered, overnight in the refrigerator. Wrap buns in foil and bake in a 300 degree F oven about 15 minutes or until heated through.