Cut a sturgeon into pieces or slices and strew with salt and pepper. Dip in flour and fry in butter until done. Set aside to cool. Arrange a border of dough around a plate, arrange the fish on the plate, and strew with grated cheese and breadcrumbs. Pour on a bechamel sauce made from strong bouillon, flour, cheese, cream, and nutmeg and bake in the oven. When it has finished cooking, decorate the top with field mushrooms and serve yellow sauce separately in a sauceboat.