1. Cut the fennel into eight pieces, place them in a sous-vide bag with 40g of butter with seaweed and bonito flakes, the juice of half a lemon, close and cook for 40 minutes at 75°C. Stop cooking by immersing the bag in an ice water bath.
  2. Rinse the potatoes and bake them for 2 hours in a preheated oven at 190°C. Push them through a strainer to remove the skins and mix in 30g of butter with seaweed and bonito flakes and 150g of hot milk using a potato masher for at least 2 minutes
  3. In a small saucepan, boil the water, mustard seeds, rice vinegar, sugar and bay leaf for 10 minutes.
  4. In a frying pan over a low heat, melt 20g of butter with the seaweed and bonito flakes, then place the sole fillets and brown them by basting them regularly with butter (add butter if necessary)
  5. In a hot frying pan, melt a little butter and fry the pieces of fennel on one side only.




  1. Place a sole fillet on each plate with some of the cold mustard seeds, mashed potatoes and fennel.