1lbwhole mushrooms, rinsed and sliced in half (or use pre-sliced)
cooked egg noodles, for serving
chopped fresh parsley, for garnish
Place beef, onion, mushrooms, worcestershire sauce, salt and pepper in a slow cooker.
Cover and cook on low 8 hours or high 6 hours, until meat is tender.
Ladle 1 cup of the liquid from the slow cooker into a medium size bowl. Add the cornstarch and whisk until smooth. With the heat still on pour the cornstarch mixture back in slow cooker and stir until combined.
Cook another 10 minutes until the sauce has thickened. While the sauce is thickening boil the egg noodles according to the package directions.
Turn the slow cooker off, or set it to warm and stir in the sour cream and Dijon mustard.
Serve over egg noodles and top with fresh parsley.