Make a quick and easy vegetarian stroganoff with mushrooms by using a packaged onion soup mix to get a creamy and flavorful base. You really don't need much to make this simple stroganoff recipe, just a packaged onion soup mix, mushrooms and a little red wine to bring it all together. Vegetarian stroganoff can be served over egg noodles, rice or baked potatoes. Be sure to use a vegan onion soup mix for a stroganoff that is both vegetarian and vegan. We got this recipe via fantastic foods.