Put one level tablespoonful of butter into a saucepan, and when melted add one level tablespoonful of flour; cook, but not brown; add slowly the stock, and stir until perfectly smooth; then add the cream; after it begins to thicken add the lobster meat, the chopped truffle, and the mushrooms cut into dice. Season highly with salt and cayenne or paprica. Let simmer for five minutes. This must be creamy, but not too soft. It can be served as filling for patties or potato croustades, or may be served in paper boxes. This amount makes about a cupful of salpicon, which is enough for six patties.