Stretch two large sheets of cling film over a work surface and spoon over some of the cure. Lay one of the fillets, skin side down, on the cure, then pack over most of the cure, and sandwich with the remaining fillet, skin side up. Top with the last of the cure and wrap both fillets together tightly with lots of cling film. Place in a container with sides, like a large roasting tray, put a smaller tray on top and weigh it down with a couple of tins. Leave in the fridge for at least three days or up to a week. Don’t be alarmed by the amount of liquid that leaks out, this is normal. Once a day, pour away the liquid, turn the salmon and re-apply the weights.