Peel and wash the salsify. Cut the stems into 15 cm pieces and place them in cold water. Melt the butter and add the quince juice, soy sauce and fish sauce. Chop the algae and add them to the butter. Combine all ingredients in a vacuum bag, seal and bake for 35 minutes in a steam oven or Bain Marie at 85°C. Remove the butter (keep it for the fish) and grill the salsify with a blowtorch just before serving.
Fillet the cusk. Portion the fillets and salt lightly. Pour the salsify butter onto an oven tray and place the fish in the butter. Brush the cusk with the butter and bake in an oven at 80 °C to a core temperature of 45 °C.
Peel the shallots and slice them thinly. Pluck the parsley leaves and remove the stems from the cress. Fry the shallots gently in a large pot, add the greens and keep frying until they wilt but without losing the green colour. Place the mixture in a blender with a little bit of cold water and mix to obtain a smooth green purée. Season with salt before serving.
Chop the shallots finely. Fry them gently with rapeseed oil in a saucepan. Add water and cook until it’s evaporated. Cut the butter into cubes and add to the onions in small batches using a hand blender with the pan on low heat. Keep mixing while adding the oysters. Before serving, add the trout roe and season with champagne vinegar and salt.
Cut the fennel into small pieces. Bring the vinegar to a boil with sugar and salt; pour the hot liquid over the fennel. Strain the fennel just before serving. Chop the jalapeño and mix it with the oil in a blender until the oil turns green. Strain the oil and keep it in a squeeze bottle until serving.