Open rare beef and mushroom sandwich

Inspired by cold days in Copenhagen where open sandwiches not only warm you up but are pretty much a work of art, this creation has all the Scandinavian flavours you might hope for. We have used two cultivated mushrooms, oysters and the eryngii, for effect, texture (and height!) and because of their availability through the winter. Scandinavia is traditionally a mushroom-foraging region and flavours used in the cuisine lend themselves well to many different mushrooms, so do experiment with