In a bowl, combine glutinous rice and enough water to cover. Soak for at at least 6 hours or overnight for best results. In a colander, drain well and transfer into a wide plate.
In a small bowl with warm water, soak shitake mushrooms until softened. Using hands, squeeze liquid and then mince.
In a bowl, combine ground pork, water chestnuts, mushrooms, ginger, green onions, garlic, soy sauce, wine, sesame oil, egg, salt and pepper. Gently stir to combine. Form meat mixture into balls of about 1-inch diameter. Gently roll each ball in rice to fully coat, pressing rice onto meat.
Line a steamer with wax paper or Chinese cabbage leaves. Arrange rice-coated meatballs in a single layer on steamer at about 1/2 inch apart. Steam for about 20 to 30 minutes or until rice and meat are cooked through. Serve with dipping sauce.
For moist meatballs, use ground pork with about higher percent of fat. If meat mixture is too soft to shape or roll in rice, freeze for about 10 to 15 minutes to firm up.