Stornoway Salmon Surprise

1. Preheat the oven to 180°C / 350F / Gas Mark 4.
2. Peel and par-boil the potatoes, drain and grate once cooled. Make the grated potato into cakes and pan fry until browned on each side, then put into the oven to cook for 15 minutes.
3. Season the salmon fillets and sear in a pan on each side, and place in an oven tray and cook for 8 minutes.
4. Heat a pan and cook the black pudding for 3 minutes on each side.
5. Put the lemon juice in a pan with the onion and reduce until there is one tablespoon left.
6. For the hollandaise sauce, place the egg yolks in a glass bowl over a pan of simmering water and add the reduced lemon juice. Whisk together until the whisk leaves ribbons and then start to slowly add the butter, until it is all incorporated. Season with salt and pepper to taste. (If you feel you need more lemon juice, add it at this stage).

To Serve:
Place the black pudding on the potato rosti and place the salmon, topped with hollandaise sauce, on top.