In medium bowl, mix herb-seasoned dry bread stuffing mix with hot water. Gradually mix in sausage until blended with the stuffing mix. Stir in onion, celery, egg and baking powder. Shape the mixture into 1-inch balls. Place the balls on a large baking sheet, cover with foil and bake in the preheated oven 15 minutes. Remove foil. Raise oven temperature to 350 º F. Continue baking 25 minutes, until golden brown.