Soak the gelatine in cold water.
Cut the potato into cubes and gently cook in water until tender.
Then cook dry.
Poach the cod until tender in the fish stock, then add the pre-soaked gelatine.
Put the potato with the cooked fish in the thermo blender and add the olive oil along with the crème fraîche, Culinaire Original and mustard.
Mix until smooth and season with salt, pepper and lemon juice.
Transfer the mixture to a piping bag and set aside cold.