Mushroom stock: Begin by bringing a pan of water to a boil. Add in the dried porcini mushrooms, the stalks from the other mushrooms in the recipe, the garlic cloves, the chervil stalks, and the shallot skins. Bring the mixture to a rapid boil and once it reduces by 1/3, take it off the heat. Pass it through a sieve and set aside.
Cauliflower mushroom scratchings: In a pan of hot oil at about 170 degrees celsius, fry the cauliflower mushroom scratchings until they puff up and are golden brown. Using a spider or slotted spoon, carefully take out the fried mushroom scratchings and place them on a plate with kitchen paper to soak up the excess oil. Season the fried cauliflower mushroom scratchings with the mushroom seasoning and set aside.
Mushroom seasoning: In a spice grinder, blend the dried porcini mushrooms with a generous pinch of salt to a fine powder.
Preparing the mushrooms: Next, finely slice the shiitake mushrooms and chestnut mushrooms. In a pan with a little oil, sear the hen of the wood mushrooms. Once they are softened and wilted, add in the sliced shiitake and chestnut mushrooms with a knob of butter.
Once the mushrooms reach a deep sear, add in a couple of grinds of black pepper, the finely diced shallots, the sliced garlic, and a big splash of Madeira wine. Then flambé the mushrooms to cook out the alcohol and reduce the liquid until almost dry.
Final steps: Once the mushroom liquid is reduced to almost dry, carefully strain in the mushroom stock through a fine sieve. Reduce the mushrooms by half, then add in a splash of cream and further reduce to coating consistency. Finish the mushrooms with some fresh tarragon and chopped chervil.
Serve the mushrooms on a bed of sourdough toast, topping them with a bright egg yolk sprinkled with salt, and garnish with the fried cauliflower mushroom scratchings and more tarragon leaves.
