Start by patting your salmon fillets dry with paper towels to ensure a crispy skin. Drizzle olive oil over the fillets and rub it in generously. Season both sides with kosher salt and cracked black pepper.

Next, preheat your grill to medium-high heat, around 400°F (200°C), while cleaning the grates to avoid sticking.

Carefully place the seasoned salmon fillets skin-side down on the preheated grill. Cook for 5 to 6 minutes until they easily release from the grates.

Using a fish spatula, gently flip the salmon fillets over and cook for another 3 to 4 minutes until the meat becomes tender and flaky.

In a small bowl, mix together the BBQ sauce, melted unsalted butter, fresh lemon juice, and garlic powder. Brush this mixture generously over the skin side of the fillets.

Close the grill lid and cook for an additional 3 to 5 minutes to let the glaze bubble and become tacky.

Using a digital meat thermometer, check that the salmon reaches 135°F (57°C) for medium-rare or up to 145°F (63°C) for well done.

Carefully remove the salmon from the grill and let it rest for a couple of minutes. Serve garnished with fresh lemon slices.