3 red chillies, deseeded and finely chopped
12 allspice berries
12 black peppercorns
3 teaspoons ground cinnamon
7 tablespoons olive oil, plus extra for drizzling
2 oranges, peeled and cut into thick slices
3 red onions, cut into wedges
4 teaspoons soft light brown sugar
6 sprigs of lemon thyme
4 bay leaves
4 mackerel, gutted and cleaned
Juice of half an orange
Preheat the oven to 170C fan/190C/gas mark 5. Use a pestle and mortar to grind the chillies, allspice, peppercorns, cinnamon and 2 teaspoons of salt together until the whole spices are roughly ground. Add the oil and grind a little more until you have a loose paste. Brush the orange slices and onion wedges with some of the spice paste (reserving the remainder for the fish) then put them into a roasting tin or ovenproof dish big enough to take the mackerel as well. Roast for 20 minutes until the onions are tender.
Sprinkle the sugar over the oranges and onions, and add the lemon thyme sprigs and bay leaves.
Wash the mackerel inside and outside and pat dry with kitchen paper. Make three deep diagonal slashes down each side of the fish with a sharp knife. Brush the spice paste all over the fish, inside and outside, working some of the paste into the slashes.
Lay the mackerel on top of the oranges and onions, arranging them so that the oranges are more exposed than the onions, as you want them to get a little caramelised. Drizzle the mackerel with a little more oil and season with salt, then squeeze over the juice from the orange half. Return to the oven for another 20 minutes and then check the flesh at the thickest part of the fish with a sharp knife to see if it is cooked. Serve garnished with roughly chopped parsley, if you like.
Taken from 'Spice It Up!' by Levi Roots (Mitchell Beazley, £18.99).