1tpsp freshly grated horseradish, or use horseradish from a jar (more or less to taste)
15ml (1tpsp) olive oil or rapeseed oil
4 x 60g steaks of wagyu sirloin, fillet or rib-eye, trimmed of sinew, at room temperature
Cress or something pretty to garnish
Cut the base from both types of mushroom then separate each mushroom from the clump – keeping them separate. Heat up a frying-pan and add half the butter and cook until it begins to turn golden. Add the shimeji and cook over a moderate heat, stirring, until they begin to wilt. Add 40ml of the soy sauce, put a lid on, and turn the heat quite low. Leave them to cook/steam for 5 minutes, shaking the pan from time to time, and keep warm.
Put the vinegar and sugar into a pan with 150ml water and 1 teaspoon flaky salt. Bring to the boil, add the enoki and take off the heat. Leave to cool in the liquid then decant into a bowl.
Peel the potatoes and halve them, then boil in lightly salted water until cooked. Drain the potato into a colander and put the pan back on the heat with the remaining butter and the cream. Bring to the boil, return the potato to the pan and mash it all together with the horseradish. Season with salt and keep covered and warm.
Heat up a heavy-based pan or skillet over a moderate-high heat. Rub the oil over the wagyu steaks and season generously with black pepper and salt. When the pan is hot, place the steaks in and cook until well coloured, then turn them over and cook the same on the other side. Sear all sides of the wagyu so it’s brown and caramelised. Take from the heat, but keep warm and covered. Rest for 5 minutes. Don’t overcook them or all their lovely flavour will be lost.
To serve: Divide the mash amongst four warmed plates. Slice the steaks in half and rest on the mash, tuck the shimeji in and then place some of the drained enoki on top. Add the wagyu cooking juices, remaining soy sauce and a little of the enoki pickling liquid to the shimeji pan juices, and use to sauce the dish. Garnish with cress.