This is delicious! Found it in an older cookbook long ago....I think it was The apartment vegetarian cookbook. I now make it pretty much from memory, since my copy deteriorated into a pile of sauce-covered pages long ago.
1 tablespoon margarine or butter
1/2 cup chopped onions
1/2 pound sliced mushrooms
A bit of salt and pepper
1 tablespoon flour
1 tablespoon soy sauce
1 cup water or stock
1/2 cup ketchup or catsup or whatever it is...
3/4 cup Parmesan cheese, grated
1 ) Saute onions and mushrooms in butter on medium heat until soft.
2 ) Stir in flour, salt and pepper. Add water and soy sauce a bit at a time until smooth. Cook a few minutes until it starts to thicken, stirring often. Stir in ketchup.
3 ) Slowly stir in Parmesan. Turn heat to low and let sit a few minutes. Serve over toast or rice.
Yes, the ketchup sounds weird. But it's so good! Also works with chili sauce, spaghetti sauce, and even salsa!