1. Heat a chargrill pan to medium-high. Season mackerel with salt and pepper. Grill, skin side down, for 6-8 minutes or until the skin is lightly charred and the mackerel is nearly cooked through (you can tell because the flesh will turn white and opaque). Gently flip fillets and grill until just cooked through, 1-2 minutes more.

2. Meanwhile, drizzle bread with olive oil and grill until lightly charred on both sides, about 4 minutes each side.

3. Rub toast with garlic halves, then top with tomato, chilli flakes, salt and sumac, if using. Top with mackerel, coriander, more chilli flakes and salt. Squeeze lemon over the whole thing to serve.

Note: If you can't find mackerel, substitute sardines or another oily fish.

Tip: If you don't have a chargrill pan, cook in an oven preheated to 250C (230C fan-forced). Place the seasoned mackerel, skin-side up, and oil-drizzled bread separately on a wire rack set inside a roasting dish. Roast, without flipping, until the mackerel skin is starting to blister, 8-10 minutes, removing bread as soon as it is browned and toasted. Assemble as per the final step.

Serving suggestion: Fennel salad with olives and lime