Pat the salmon dry with paper towels on a rimmed tray. Check for pin bones and remove any with clean tweezers. Refrigerate while the grill heats.

Set up an outdoor grill for medium-high direct heat, about 400°F (205°C), with a cooler area available. Clean the grates with a bristle-free scraper and preheat with the lid closed according to the grill manufacturer's instructions.

Rub the avocado oil lightly over the flesh and skin of the salmon. Season with the kosher salt and black pepper.

Place the fillets skin-side down on the hot grates, leaving space between them. Close the lid and cook without flipping. Begin checking after 8 minutes; 1-inch fillets usually take about 10–15 minutes, but thickness and grill heat vary. If the skin is darkening too fast, gently move the fillets to the cooler area and continue covered.

Insert a clean instant-read thermometer sideways into the thickest part of each fillet. Cook until the center reaches 145°F (63°C) before removing; the flesh should be opaque and separate into flakes. Lift with a wide fish spatula onto a clean plate and serve with the lemon wedges.