Spray a large slow cooker with non-stick cooking spray. Place the roast in the slow cooker. You do not need to sear the roast for this recipe.
In a medium bowl, add the sour cream, milk, Lipton Onion Soup Mix, Brown Gravy Mix, dijon mustard, and cream of mushroom soup. Whisk until well blended.
Add sliced mushrooms to the sour cream mixture and stir until fully incorporated.
Pour sour cream sauce mixture over the roast and cook on LOW for 6-8 hours.
Buttered Egg Noodles
When roast is cooked through, prepare the egg noodles. Fill a large pot with 12 cups of water. Add salt and bring water to a boil. Add egg noodles and cook until tender, about 10 minutes.
Drain egg noodles and add them back to the pot. Add butter and blend until melted. Pour noodles into serving dish and top with beef stroganoff, ladling the sour cream sauce over the noodles.
Serving Suggestions: Slow Cooker Beef Stroganoff is best served with egg noodles or rice.Freezing Option: This recipe is excellent when reheated. If the recipe makes more than you need, simply freeze half for later.