– Cut off the head, tail and fin of the fish. Cut in two fillets along the spine and remove the bones. Slice the flesh from the skin and chop.

– Beat the butter by hand or in the mixer

– Put the fillet in a rectangular even layer, smear with 3 mm butter and roll tight. Wrap in parchment or foil and keep in the refrigerator

– Slice into rings, put in a plate, decorate with the lemon and greens when serving