This one came together quite serendipitously: I was determined to cook two fillets of Icelandic cod and entertained vague ideas of pan-frying. In the meantime the baby potatoes I had cooked alongside the roast chicken from the other night were haunting me with the memory of their crisp, taut skins and melting insides that burst in the mouth like a kind of starchy xiao long bao. I had also been leafing through a cookbook in which chicken was steamed with a topping of spring onions, and this was also wafting through my mind. In the end, this was the recipe that emerged.
Take a generous amount of very small potatoes with their skins still on, and macerate them with a very generous amount of goose fat, sea salt, and rosemary or dill. Roast in a preheated oven for about thirty minutes. Meanwhile, prepare the fish: make parcels by laying them out on large sheets of aluminium foil. Start with two slices of lemon, then the fish, generously seasoned with salt and pepper, and then two slabs of good butter, sliced leeks, a mound of enoki mushrooms, another slab of butter, and then another slice of lemon and a sprig of dill. Wrap the whole thing up, one for each fillet, and place on top of the potatoes and bake for another twenty to thirty minutes. When opened the fish should be meltingly tender in a lemony-butter sauce, and the mushrooms soft but still with a bite to them. Serve by folding the parcels into a boat shape or transferring onto a plate; serve with the potatoes, which we dubbed Keith Richards potatoes for their leathery quality, in a big dish on the side.
