1. Place the mackerel fillets into the cucumber and summer cup brine for 30 minutes. 2. Then drain the fillets. 3. Cut them down the middle so you have 8 belly fillets and 8 ‘royal’ fillets.

Add the icecubes and when cool add the mackerel – making sure they’re covered. Leave for 30 minutes then remove from brine and pat dry. Brush with oil and sprinkle over the ground coriander ...