Make diagonal slashes in the salmon skin with a sharp knife and smear the pesto over the top. Using the back of the spoon, press the pesto into the slashes in the fish.
Pop the salmon, skin side down, in a hot, dry pan to sear the skin - this should take around 30 seconds. Place the salmon on a baking tray or oven-proof dish and roast for approx 10 minutes or less, depending on how you like your fish.
Serve with mashed potatoes, salad or oven-roasted vegetables.