Fresh dill sprigs, optional In large bowl,combine egg,bread crumbs,club soda,2 tablespoon. chopped dill, 0.75 tsp. salt and quarter tsp. pepper;using hands or wooden spoon, blend well.Shape mixture into 3 cm balls.In 30 cm skillet,over medium-high heat,melt 2 tablespoon. butter;add meatballs;cook about dozen minutes, turning frequently until browned on all sides.Meanwhile,prepare noodles according to package directions,add green beans to boiling water along with noodles;do not add salt.When meatballs are browned,remove to plate using slotted spoon.To drippings in skillet,add remaining 1 tablespoon. butter;melt over medium-high heat.Add mushrooms;cook about 5 minutes, stirring frequently until crisp-tender.Return meatballs to skillet along with 0.75 cup water and remaining 1 tablespoon. chopped dill, half tsp. salt and quarter tsp. pepper.Increase heat to high;bring to boil.Reduce heat to low;cook,covered,5 minutes until meatballs are cooked through. Stir in sour cream;cook 2 to 3 minutes longer until heated through. To serve:Drain noodles and green beans;arrange on serving platter. Spoon meatball mixture over noodles;toss quickly.Garnish with dill sprigs,if desired.Makes 4 servings.