Prepare sweet and sour sauce; set aside. Also prepare lumpia wrappers and set aside. Soak mushrooms in warm water to cover for 30 min., then drain. Cut off and discard stems; finely chop caps. Crumble porc into a wide frying pan. Add onions and garlic and cook over med. high heat, stirring, until meat is browned (about 6 min.) Add shrimp, mushrooms, and water chestnuts and cook for 2 min. Stir in soy. Let cool; then discard excess pan juices. Fill and fold lumpia ,start from a corner Diamond wise, then roll up bringing the sides in, moistening wrapper edges with egg to seal. ( at this point you may cover and refrigerate for up to 8 hours.) Into a 2 to 3 quarts pan, pour oil to a dept of 1-1/2in and heat to 340deg. on a deep frying thermometer. (If using egg rolls, heat to 360deg.) Add 4 or 5 lumpia; cook, turning as needed, until golden brown (2-3 min). Remove with a slotted spoon and drain on paper towels; keep warm in a 200deg. oven. Repeat with remaining lumpia. Serve with sweet & sour sauce.