Preheat the oven to 450F or 425F convection. Line a baking sheet with parchment paper.
Add potatoes to the baking sheet and toss with 2 tablespoons oil and ½ teaspoon salt to coat. Spread the potatoes out into an even layer, placing them cut-side-down. Bake for 20 minutes or until light golden brown on the bottoms.
Drizzle remaining 1 tablespoon oil all over the salmon and sprinkle remaining ½ teaspoon salt and ½ teaspoon pepper all over the flesh.
Reduce the oven temperature to 400F. Make four spaces for the filets on the baking sheet and place them skin-side-down. Bake for another 10 minutes, or until the salmon is cooked through.
In a high-speed blender, add the herbs, peas, nuts, parmesan, lemon zest + juice, salt, and garlic. Blend until finely chopped, scraping down the sides and under the blade as needed. With the motor running on low, slowly drizzle in the olive oil. Continue blending until mostly smooth.
Serve the salmon and potatoes topped with the pesto, lemon wedges, and a simple side salad if you’d like.