This works better with dried morels (which have an intense smoky flavor) than with fresh. It is excellent with grilled vegetables and fish. Rinse ½ ounce (15 grams) dried morels under cold running water and soak them in a bowl with ½ cup (125 milliliters) Madeira. When the morels are soft, put them in a saucepan with the Madeira (be careful to leave any grit in the bottom of the bowl), partially cover, and cook them for 5 minutes. Remove the morels and cook down the Madeira until only 1 tablespoon (15 milliliters) remains. Chop the cooked morels and add them and the reduced Madeira to 1 cup (250 milliliters) mayonnaise. Add 1 to 2 tablespoons (15 to 30 milliliters) wine vinegar, to taste. Season with salt and pepper.