At first chop cleaned onions and mushrooms.
In a pot with heated oil let fry the onion. Then add mushrooms, salt and grate the nutmeg. After couple minutes of frying pour in the water.
On a side stir flour into a cream and after 20 minutes of cooking, thicken the gravy with it. Again, grate the nutmeg in it, add vinegar to sour it and salt. All to your taste.
Serve the gravy with meat and dumplings or rice.