Soused mackerel with cucumber salad

If you are filleting the fish yourself, don’t buy them gutted. It’s easier to take the fillets off when they are whole. Make an incision behind the head then run your knife down the backbone and keep cutting in long sweeping strokes close to the bone until the fillet comes away.

If you’re feeling brave, you can remove the pin bones by making a v-shaped incision down the middle of the flesh side of the fillets and removing the bones in one line (don’t go through the skin). If not, you can take them out with tweezers after sousing, when it will be easier.

Salting the fish. This will start to draw out moisture from the fillets and begin the curing process. Sprinkle ½ tbsp of sea salt in the bottom of a dish that will take the fillets in one layer. Put the mackerel in flesh-side down then sprinkle another ½ tbsp salt on top. Chill for 2-3 hours.

Making the sousing liquid. Bring 1 litre of water to a boil in a large pan. Add the vinegar and sugar and stir until dissolved. Add the spices and vegetables and season with a little more sea salt. Turn off the heat and let the liquid cool down completely.

Sousing the fillets. Brush any excess salt from the fillets then pour over the cooled liquid. Cover with clingfilm then put in the fridge and leave for 24 hours.

Finishing the dish. Peel the cucumber, turning all the time so you end up with pappardelle-style ribbons (stop when you reach the seeds). Dress the cucumber with a little sousing liquid, some olive oil and seasoning. Mix the horseradish and crème fraîche.
Cut the mackerel into pieces of 4 or 5. Pile cucumber in the centre of each plate and surround with mackerel. Dress the plates with some veg and a little sousing liquid, then put a quenelle [a small scoop] of horseradish cream in the middle and drizzle a little more oil over the fish.