Preheat oven to 375°F. In a large skillet, heat oil over medium heat and sauté onion until translucent (about 5 minutes). Add coleslaw mix and sauté until mixture is wilted about 5 minutes; stir in optional sauerkraut or kim chee. Stir in corned beef, salt and pepper and set aside. On a lightly floured surface, unfold puff pastry sheet. Cut 9 (2 3/4-inch) squares from each sheet. Transfer half of the squares onto two baking sheets lined with parchment paper. Fill the center of each puff pastry square with 1 rounded tablespoon of corned beef mixture. Moisten edges of each square with water. Take another square, stretch it slightly, and then place it on top of the filling to cover (like a ravioli). Use a fork to press the edges together and seal. Repeat for all squares. Brush tops with beaten egg. Bake about 20 minutes or until golden brown. In a small bowl, mix mayonnaise and mustard; serve as a dip with turnovers. Makes 6 servings.