OPTIONAL: Heat a ridged frying pan over high heat and brush the orange slices with olive oil. Fry the orange slices in batches, turning once, until there are char lines visible on both sides. Set aside.

Prepare a fire in your kettle barbecue - you will need 15-20 charcoal briquettes, piled together on the lower grill and lit using firelighter cubes. When they are mostly grey and ashed over (20 mins or so), spread the coals out a little in the centre of the lower grill, put the top grill in place and close the barbecue lid, leaving the top and bottom vents open. Give the barbecue about 10 minutes to get to 150-180C.

While the coals are getting ready, lightly oil a large foil roasting dish, big enough to accommodate the fish in a single layer. Lay the fish skin side down in the oiled roasting dish and season lightly with salt and pepper.

Melt the butter, capers, chopped dill and zest together in the microwave (or on the stovetop in a small saucepan) until the butter is just melted. Mix well and add a good grind of black pepper.

Tuck the orange slices and half the remaining whole dill fronds around and under the fish (reserve the rest of the dill for garnish). Baste the fish liberally with the seasoned butter and place the roasting dish uncovered on the top barbecue grill directly above the charcoal.

Close the lid and leave to cook for 15 minutes. Try not to open the lid during cooking as this will cause the temperature to drop. After 15 minutes, check the thickest part of the fish to see if it is done (it should flake easily with a fork).

Once the salmon is done, carefully lift it off the skin using an egg lifter or fish server, and serve decorated with the orange slices and the remaining dill fronds.