Trim fresh mushrooms and slice thinly. Soak dried mushrooms in hot water until softened; drain and mince. Saute fresh mushrooms and shallot in butter over high heat. When mushrooms start to release juices, add dried mushrooms. Cook over low heat until liquid is reduced by half. Add stock, soy sauce and sherry. Cook, stirring, until most of the liquid is evaporated. Add cream; cook, stirring, until mixture is thck and cream coats mushrooms. Serve in baked polenta cups or puff pastry bouchees.