Dry sliced mushrooms in a low oven overnight.
Fry shallots and garlic in oil, then add thyme and dried mushrooms.
Add madeira, reduce by two thirds, add 1.5 litres water and simmer for 2 hours.
Cool stock at room temperature, then refrigerate overnight.
Sieve stock, reduce by half and season with salt and pepper.
Freeze sliced mushrooms, mix with salt, and ferment in a warm place for 24 hours.
Boil 2 litres water with salt, cool, add dill, and brine cabbage halves for 20 minutes.
Blend eggs, vinegar, salt, and mustard, then emulsify with sunflower oil.
Pour emulsion into a cream whipper, charge with two bulbs, and keep warm at 50°C.
Reduce stout vinegar by two thirds and simmer mead to evaporate alcohol.
Combine mushroom stock, sugar, and mushroom juice with mead and reduce slightly.
Thicken the sauce with kuzu paste and stir in the reduced vinegar.
Preheat oven to 180°C.
Sear cabbage in oil and butter, then roast in the oven for 6 minutes.
Sauté wild mushrooms and onions in butter, wilt garlic leaves, and season.
Spoon sauce into bowls, place cabbage inside, and top with mushroom mixture, emulsion, and truffle.