Trim the char and cut it into portions. Place the fish skin down on a tray with a silicone sheet and salt lightly. Grill the butter by melting it and dipping a piece of burning charcoal into it. (For an easier recipe, use the butter without grilling it). Heat the butter with Espelette pepper and thyme. Before serving, brush the fish with the grilled butter and turn the fish skin side up. Bake in the oven at 105°C for 6 minutes and remove the skin gently.
Combine the egg with miso and mustard. Incorporate the oil slowly using a hand blender. Season with salt and rice vinegar.
Cut the cauliflower into small pieces and boil it in water until soft. Drain the cauliflower and press out any excess water. Mix in a blender with yoghurt and butter to obtain a smooth purée. Season with salt and lemon juice.
Peel the cucumber and mix the peels with salt, sugar, water, sour beer and the coriander roots in a blender to obtain a green liquid. Strain and keep the liquid. Make pearls of the cucumber using a parisienne scoop and marinate the pearls in the green liquid.
Cut the cauliflower into small bouquets and marinate in the pickling liquid and the yuzu.
Place the trout roe in a piping bag. Fry the chips in a sauce pan with oil at 225°C. Drain on paper towels and salt lightly. Pluck the herbs into cold water.