Follow these steps:
1.Brush and take the stems off the mushrooms. Heat up a frying pan with butter and let the butter turn brown, then place the mushrooms in the hot butter and turn down the heat: fry them on one side for one minute than turn them and place the pan in the oven at 85°C for 20 minutes.
2.Heat up a pan with the chicken fat and roast the buckwheat until golden. Let it drain on paper and sprinkle some salt on it.
3.Whisk the egg yolk and mustard while slowly pouring it in the oil. Flavor with white soy sauce and tabasco.
4.Pipe the soy mayonnaise into the mushrooms, sprinkle some buckwheat and sliced truffle on top, then finish off with dried edible flowers.