Mix oatmeal with water and add the bread. Let stand at least 24 hours until it sours. Strain. Cook sausage in water for one hour. Remove sausage and skim the fat accumulated in the water. Add liquid to the oatmeal mixture. Mix in a tablespoon of horseradish. Serve hot with slices of Polish sausage and hard-cooked egg, boiled potatoes or cro