Created by KittenCal on August 11, 2011
Step 1: Heat butter and oil over medium heat in a large skillet.
Step 2: Add in frozen hamburger patties; cook turning frequently until browned on each side (the patties do not have to cook all the way through they will finish cooking in the sauce).
Step 3: In a bowl whisk the mushroom soup with next 5 ingredients until thoroughly combined.
Step 4: Pour over patties (turning the patties a few times to coat in the sauce).
Step 5: Mix in the mushrooms.
Step 6: Simmer uncovered for about 30-40 minutes turning the burgers frequently and seasoning with more black pepper if needed.
Step 7: About 5-7 minutes towards the end of cooking mix in the sour cream and heat through.
Step 8: Serve with fries or mashed potatoes.