Filling: Chop chicken in pieces and stir fry with garlic in a little oil about 2-5 minutes, remove and set aside. Heat a little more oil. Add all vegetables except water chestnuts and fry until tender, stirring constantly. Add chicken, fry 5 minutes longer.
Mix together soy sauce, cornstarch and sugar. Pour over chicken mixture. If getting too thick add soy sauce. Grate ginger root over entire mixture until you can smell it. Simmer 5-10 minutes adding water chestnuts.
Place egg roll skin with one point towards you. Spoon 1/4 cup of filling diagonally across just below center. Fold bottom point of skin over filling. Fold side points over, forming envelope shape. Roll up toward remaining corner; moisten point with water and press firmly to seal. Repeat with remaining skins and filling.
Fry egg rolls a few at a time in hot oil for 3 minutes or until golden brown. Drain on paper towels. Serve warm with plum sauce, hot mustard.
