Combine all ingredients for meatballs. Mash well until all ingredients thoroughly incorporated.
Shape into 1 1/2 inch balls and lay out on cookie sheet.
Bake at 350 for 20 minutes.
While baking meatballs, melt butter in large wok.
Add onions to butter and simmer until transparent.
Add mushrooms and continue to simmer about five minutes.
Add 1/2 cup flour and simmer, stirring constantly, until thoroughly incorporated.
Add broth, milk, beer, Worcestershire sauce, salt, and pepper.
Stir constantly until well combined.
Transfer to slow cooker.
About one hour before serving, combine 3/4 cup flour with 1 cup of mushroom gravy juice and stir slowly into cooker until well combined.
Set slow cooker to low, stirring occasionally, until thickened.
Turn cooker to warm and keep warm until serving.
Just before serving, stir in sour cream until well combined.
Serve with noodles, rice, or perogies.