Slice onions (cut in half and cut each half into thin slices).
Add all ingredients except sour cream to crockpot and stir well to combine.
Cook in crockpot for at least 8 hours at Low.
Remove bay leaf, meat and onions from crockpot. Don't worry if you can't get all the onions out! Discard bay leaf.
Check seasoning and add salt and pepper if required. I find almost everything needs salt and pepper after it's been cooked in the crock.
Add sour cream to liquid in crockpot and stir well until combined.
Put meat and onions back in crockpot and stir to combine with sauce.
Turn crockpot to High for 15 minutes to heat through.
Stir well and serve with noodles, rice, or pierogi.