Brown ground beef in a skillet; drain off any excess fat.

Add sliced onions and minced garlic to the skillet.

Sauté until the onions are wilted and translucent.

Sprinkle flour, salt, pepper, and paprika over the beef and onion mixture.

Stir well to combine and coat the beef and onions.

Stir in the undiluted cream of celery or mushroom soup until well mixed.

Transfer the mixture to a crock pot.

Cook on low setting for 6 hours.

Shortly before serving, add sliced mushrooms (optional).

Stir in sour cream until well combined.

Serve hot over noodles, rice, or mashed potatoes.