Combine stew meat, chopped onion, minced garlic, flour, Hungarian paprika, and salt in a slow cooker.

Stir well to coat the beef and onion in flour.

Combine diced tomatoes, liquid gravy browner, beef bullion powder, lemon juice, and sugar together in a separate bowl.

Pour the tomato mixture over the beef mixture in the slow cooker.

Stir to combine.

Cover the slow cooker and cook on low for 8-10 hours or on high for 4-5 hours.

Spoon a few spoonfuls of liquid from the slow cooker into a separate bowl.

Add sour cream to the liquid in the bowl and stir until smooth.

Pour the sour cream mixture back into the slow cooker.

Stir well to combine.

Serve hot over boiled egg noodles.