It’s the raisins and the sherry that do it for this dish.
Cover the unpeeled onions with hot water. Bring to a boil and remove from the heat. When the onions are cool enough to handle, peel, scraping the root ends (do not cut). The skins will slip off easily.
Bring the 1 quart water and salt to a boil and add the peeled onions. Cook until barely tender, about 150 minutes. Drain, reserving the 1-¼ cups onion water.
Heat the butter or margarine, mix in the flour and stir until bubbly. Add the 1-¼ cups onion water and cream. Bring to a boil and simmer for 10 minutes, stirring.
Heat the sherry and add the raisins. Let stand for 50 minutes. Add this to the sauce with the drained onions. Heat but do not boil. Serve with a dusting of paprika.