This dish is perfect for eating al fresco. Enjoy these sandwiches on one of those first spring afternoons when the warm sun finally breaks through after a long winter. Although these are essentially glorified sandwiches, they are full-on flavour: chilli, garlic, lime, salty capers, cooling cucumber, all brought together by some tasty grilled mackerel and a dollop of mayonnaise.

Method

• Using a peeler, peel ribbons from the cucumber, turning it as you go to get ribbons of an equal width. Once you reach the seeds at the centre, discard this part.
• Mix the vinegar with the sugar, salt and chopped chilli. Drop in the cucumber ribbons and marinate for 10 minutes before draining.
• Mix together the salsa verde ingredients.
• Preheat a grill to its highest setting.
• Season the fish with salt and black pepper and rub with olive oil.
• When the grill is hot, place the fillets, skin side up, on a lightly greased tray and grill for 4 minutes until the skin is crisp and the flesh is cooked. Remove from the grill.
• Lightly toast the bread, spread mayonnaise on 4 of the slices and lay 2 fish fillets on each. Spoon over the salsa verde and then top each off with some drained cucumber. Cover with some rocket and the remaining slices of toast.

@alanrosenthal