Fennel:
Clean the fennel and shave thinly on a mandolin length ways, season with sea salt and the rapeseed dressing. Layer on top of each other and leave for 10 minutes to semi cure.
Hake:
Cover the hake in salt and keep in the fridge for ten minutes. Was well in cold water to remove all the excess salt and drain well. Wrap in a tea towel and leave for 2-3 hours in the fridge.
To finish:
Portion the hake into 4 equal pieces and leave out for 10 minutes to come to room temperature. Melt the butter in a pan gently, ensure the butter is around 2 inches deep in the pan and that it is big enough to hold all the portions of hake. Probe the butter to around 45C and add the fish, make sure the temperature stays between 40C and 45C after about 6/7 minutes check that a skewer slides through the fish without resistance. Spoon the fish into a bowl and top it with the fennel and a selection of sea vegetables and seaweed. Add a tiny amount of lemon juice to the butter and dress the dish with the butter before serving.