Step 1 In a large, wide bowl, mix together the pork, shrimp, scallions, garlic, ginger, water chestnuts or jicama, Chinese white rice wine or gin, egg whites, 1 teaspoon salt, sugar, soy sauce, sesame oil, oyster sauce and white pepper until thoroughly blended. Use your hands if necessary. Refrigerate, uncovered, for 4 hours, or cover and refrigerate overnight.
Step 2 To make won tons, work with one won ton skin at a time, keeping the remainder under a damp towel. Keep a bowl of water at hand to wet the edges of the skins. Dust a baking sheet with the cornstarch and set aside. Place about 2 teaspoons of filling in the center of a won ton skin, wet the edges, fold in half into a triangle and seal the edges. Fold the point of the triangle to the long edge. Moisten the remaining two triangle points and bring them together to form a packet, pressing to seal. Place on the baking sheet. Repeat until all the filling is used.
Step 3Place 15 cups water, the peanut oil and the remaining salt in a large pot, cover and bring to a boil over high heat. Add the won tons, stir and cook for about 8 minutes, until the won tons are translucent and the filling can be seen through the skin. Turn off heat, run cold water into pot and drain. Serve immediately.