Position your oven rack 6 inches from the broiler element - this is usually the second-highest position. Preheat broiler on high for 5 minutes. Line a rimmed baking sheet with foil and brush lightly with oil.

Pat salmon completely dry with paper towels - this is crucial for browning. Brush flesh side with 1 tablespoon olive oil, then season evenly with 1/2 teaspoon salt and all the pepper. Arrange skin-side down on the prepared pan, leaving space between fillets.

In a small bowl, stir together pesto, panko, Parmesan, and remaining 1/4 teaspoon salt. The mixture should be thick and spreadable. If your pesto is very oily, add another tablespoon of panko.

Broil salmon for 3 minutes without the topping - you want the surface to just start setting and turning opaque. This prevents the pesto from sliding off.

Remove pan from oven. Spread pesto mixture thickly over each fillet, pressing gently to adhere. Return to broiler and cook 4-5 minutes more, rotating pan halfway through, until topping is bubbling and deeply golden in spots and salmon flakes easily. Internal temperature should read 125F for medium or 130F for medium-well.

Let rest 2 minutes on the pan - the topping will set slightly. Squeeze fresh lemon over each fillet and serve immediately with the remaining lemon wedges.