Step 1

Cook ground beef and diced onion in a 10-inch skillet over medium heat, stirring occasionally. Add mushrooms after 5 minutes and cover with a lid. Simmer until the mushrooms are tender. About 8 minutes.

Step 2

Add cream of mushroom soup and mustard. Continue to simmer until heated through. Remove the skillet from the heat source and stir in sour cream.

Step 3

Serve warm over egg noodles, spaetzle, rice, or mashed potatoes.