500g (1 1/4 lb) wood chips, soaked in water or wine and squeezed dry
Rinse the fish fillets and place them in a shallow glass baking dish. Drizzle olive oil over the fish and season with garlic and rosemary. Rub the seasonings into the fish. Cover and refrigerate overnight.
Dissolve the curing salt in the water and pour into the dish with the fish. Let it marinate for 15 minutes per 1cm (1/2 in) of thickness.
Meanwhile, prepare your charcoal barbecue for a four hour slow burn. Light and wait for the grey ash to cover at least 90 percent of the coals. The temperature should be at 65 degrees C before you get started.
Remove the fish from the brine and discard leftover liquid. Place each piece of fish onto a small piece of aluminium foil - just big enough to hold the fillet, and season with pepper to taste. Place the fillets on the cooking rack. Sprinkle a handful of the soaked wood chips over the coals. Cover and allow fish to smoke for 2 hours, adding more wood chips as needed.
Increase the heat in the smoker (add more charcoal) to 95 degrees C and let the fish smoke until the internal temperature of the fillets reaches 70 degrees C. Remove from the smoker and let rest for 20 minutes before serving.