Serves 4
Spicy butter
For the spicy butter, drain the chillies, reserving their soaking water. Cut the tops off the chillies, then roughly chop, removing the seeds if you like. Toast the cumin and coriander seeds in a dry frying pan over medium heat until fragrant then grind to a fine powder using either a spice grinder or a mortar and pestle. Transfer to a blender, along with the chillies, garlic, olive oil, 1 teaspoon of salt and 2 tablespoons of the reserved soaking water, and blend to a rough paste. Put the chilli paste and butter into a food processor and blitz to a purée. Add the lemon juice and pepper and process for a further minute. If using straight away, set the spicy butter aside in a bowl (not in the refrigerator). Otherwise, roll it in a sheet of baking paper or foil to form a log about 35cm (14 inches) long and 4 cm (1½ inches) in diameter then wrap in plastic wrap and refrigerate until firm; the spicy butter will keep for 2 weeks in the fridge, or up to 6 months in the freezer.
Prawns
Preheat the oven to 180°C (350°F).
Place the prawns on a chopping board, legs facing up, and use a sharp knife to cut them almost right through. Open them out so they’re flat and devein. Lay the prawns on a baking tray and sprinkle with salt. Divide the spicy butter between the prawns, smearing it over the flesh, or if using chilled spicy butter, cut 5 mm (¼ inch) slices from the log and place along each prawn. Roast for about 10–12min – you want the butter to be melted and the prawns just cooked.
To serve
To serve, lay three prawns, side by side, on each plate and spoon over some of the melted butter from the baking tray.
Sprinkle with a little salt and a good grind of pepper then squeeze the juice from a lime half over each plate.
Finish with a drizzle of olive oil and a sprinkling of chives.
Tips
It’s worth making plenty of the spicy butter, as you’ll soon find endless uses for it – it’s great with steamed corn or asparagus, pan-seared fish or sea scallops, or with roast chicken.
If you have no time to make the spicy butter, just stir some bought harissa through softened butter and this dish will practically make itself.