Chiodo's Mystery Sandwich Cook hamburger patty. Top with thin slices of kolbassi and sauerkraut (see below). Heat through. Top with "mystery cheese" (a slice of provolone and a slice of American, with three pepperoni slices between) and "mystery sauce" (see below). Heat until melted. Sauerkraut: Drain and rinse kraut. Add red and green pepper, garlic, sugar, oregano, red-pepper seeds and tomato sauce. Bake at 350 degrees for 1-1.5 hours, depending on your crunch factor. Add seasonal vegetables to taste. Mystery sauce: Mix tomato sauce or puree with tomato juice to make a "not-too-thick/not-too-thin" sauce. Add red-pepper seeds, sugar, oregano, garlic, pepper, and whatever floats your boat. There are no measurements. That's what makes it a mystery every time. [According to Marcia Anderson, who served the sandwich for years.]