Prepare the Salmon: Pat the salmon fillets completely dry with a paper towel. This is crucial for getting a good sear and crispy skin. Rub both sides of each fillet with olive oil and season generously with sea salt and black pepper.

Preheat the Grill: Preheat your outdoor grill or indoor grill pan to a medium-high heat, around 200°C (400°F). Make sure the grates are clean and well-oiled to prevent sticking.

Make the Garlic-Butter Sauce: While the grill heats up, melt the butter in a small saucepan over a medium-low heat. Add the minced garlic and cook for about 1-2 minutes, stirring constantly, until it's fragrant. Be careful not to let it brown or it will taste bitter. Remove the pan from the heat and stir in the lemon juice, chopped parsley, and optional red pepper flakes. Set aside.

Grill the Salmon Skin-Side Down: Place the salmon fillets on the grill, skin-side down. Let them cook undisturbed for 5-7 minutes. The skin should be crispy and release easily from the grill when it's ready to be flipped. You can check by gently lifting a corner with a fish slice.

Flip and Baste: Carefully flip the salmon fillets. What works best for me is using a wide, flexible fish slice to get right under the fillet. Once flipped, generously brush the tops with some of the prepared garlic-butter sauce.

Finish Cooking: Grill for another 3-5 minutes on the second side, or until the salmon is cooked to your liking. The internal temperature should reach 63°C for it to be safely cooked, according to the Food Standards Agency. It should flake easily with a fork.

Rest and Serve: Remove the salmon from the grill and let it rest for a couple of minutes. This allows the juices to redistribute. Serve immediately, spooning the remaining warm garlic-butter sauce over each fillet.