Halibut with potato, pepper dulse and fennel

Weigh the sliced fennel in a bowl, then add 2% of the weight in salt. Mix the two together and pack into a clean sterilised fermentation jar. Top up with filtered water and place ceramic weights on top so the water covers the fennel. Cover the jar with muslin or a tea towel and use an elastic band to fix securely – this allows gases from the fermentation to escape but stops anything bad getting in. Allow to ferment at room temperature for about 4 days

Once the fennel has finished its fermentation, close the jar and store in the fridge

Clean and trim the halibut fillet until you have the portion sizes you like. Set aside on a piece of kitchen towel until ready to cook

Boil the potatoes until tender, then strain off the water. Leave the potatoes in the pan to continue to steam and lose as much moisture as possible. Meanwhile, in a separate pan, warm the buttermilk and butter together. Pass the cooked potatoes into a large mixing bowl through a fine sieve or potato ricer and mix the buttermilk and butter mixture into the potatoes. Season to taste with salt and in small batches in your blender, blend to bring together for very short bursts (the blender makes the potato gluey so keep in mind that you must not blend too much). Season and keep warm in a pan until ready to serve

When you’re ready to serve, season the halibut, place on small sheets of silicone paper and steam until the fish is just cooked through (about 2 minutes for a 100g portion). Warm the fermented fennel gently in a pan. Place 20g of the fennel on the bottom of each plate and top the fennel with a piece of the steamed halibut. Pour the potato mousseline over to cover the fish. Season the top of the fish with pepper dulse (or other seaweed) and serve