For the mackerel:
Mix all ingredients together. Cover the bottom of a tray in cure mix and place the skinned mackerel evenly on the mix. Cover mackerel in cure mix and leave for 30 minutes. Rinse off cure mix under some water and dry off in jay cloths. Remove the bones down the middle with a knife being careful to get all the bones out. Dice the boned mackerel into 1cm cubes and drizzle over the oil.
For the skyr:
Mix the skyr, chopped dill and lemon zest together and place in the fridge.
For the crushed potatoes:
Dice the shallots and garlic place in a pan with the butter and heat gently until they start to soften then remove them from the heat and leave to cool for ten minutes. Simmer the potatoes in heavily sated water for approx 15 minutes until tender and soft. Strain and leave to cool slightly. Add the shallots and garlic butter to the potatoes with the chopped lovage and lemon zest and crush the mix with a fork then check for seasoning.
For the pickled veg:
Place all the ingredients apart from the beetroot and shallot in a pan and bring to the boil, simmer for 20 minutes then leave to cool. Slice the beetroot into slices of 1mm thick then cutout with a 2cm metal ring cutter. Place the beetroot discs in a plastic tub and cover with half of the pickle liquor. Peel the shallots (keeping the flesh in-tact) and slice in 2mm wide rounds. Separate the layers of shallot into rings and place in a tub with the remaining pickle liquor. Leave both the pickled veg in the liquor for at least 2 hours.
Squid ink crisp:
Combine the tapioca and water in a pan and bring to the boil, simmer for 20 minutes stirring continuously until the pearls turn translucent. Strain the tapioca and place in a bowl, add the squid ink and zest and stir in until fully incorporated. Spread the tapioca and squid ink mix on to acetate and dehydrate at 60°c for 4 hours until crisp. Cut the tapioca into 10cm squares and deep fry in vegetable oil at 170°c for 10 seconds until it puffs out to around double its original size.