Disjoint chicken wings, discarding bony tips. Arrange meatier wing parts in shallow baking pan. Combine soy sauce, brown sugar, butter, mustard and water and heat until sugar and butter dissolve.
Cool and pour over wings. Marinate in refrigerator 2 hours, turning occasionally. Bake, in marinade, at 350 degrees 45 minutes, turning once and spooning marinade over chicken occasionally. Drain on paper towels and serve hot or cold.
Note: Marinade goes along way. More wings can be added. Marinate in 2 large ziplock bags.