Add ground beef and mix gently but well. Shape into 24 (1 1/2- inch) balls.
Brown meatballs in vegetable oil; drain fat. Add broth, mushrooms and onion.
Cover and simmer for 30 minutes.
Combine sour cream, flour and 1 teaspoon dill weed. Stir into broth. Cook and stir until mixture thickens and bubbles.
1 cup flour
1/2 teaspoon salt
1 egg, beaten
1/2 cup milk
Combine flour and salt. Add eggs and milk; beat well. Let rest 5 to 10 minutes. Place batter in coarse-sieved colander or deep fryer basket. Hold over large kettle of boiling water. Press batter through colander with back of wooden spoon or spatula. Cook and stir 5 minutes; drain.
To serve, make a nest of spaetzle on a large platter. Spoon meatballs and sauce in center.
Note: Dill weed can be added to spaetzle batter for this dish. A spaetzle maker (found anywhere cookware is sold) can be used instead of a colander. A spaetzle maker resembles a large garlic press.