In a mortar and pestle, grind the lemon zest and rock salt together until they are combined and have a similar texture to table salt.
Rub olive oil into the salmon fillets and place skin-side down on an oven tray lined with Glad baking paper. Sprinkle with the lemon salt and grind black pepper generously over the top. Cover loosely with Glad foil.
Place the tray in the oven for 10 minutes, then remove the foil and bake for a further 10 minutes or until the fish is cooked to your liking.
Rest the salmon for 5 minutes, loosely covered with foil.
Serve onto warmed plates, with lemon cheeks and a warm creamy potato salad on the side.