Preheat oven to 450F or 425F convection. Line a baking sheet with parchment paper.
Add potatoes, zucchini, 2 tablespoons olive oil, ½ teaspoon salt, and a few cranks of black pepper to the baking sheet and toss to coat. Spread into an even layer and bake for 15-20 minutes, or until potatoes are golden and cooked through.
Remove the baking sheet from the oven and create 4 spaces for the salmon. Place salmon on the baking sheet and drizzle each filet with remaining 1 tablespoon oil and sprinkle with remaining ½ teaspoon salt and some black pepper. Bake for 10-15 minutes or until salmon is cooked through.
In a high-speed blender, add the herbs, seeds, water, lemon, oil, soy sauce, garlic, and salt. Blend at a low speed, slowly increasing to high until smooth, scraping down the sides as needed (this will take a minute or so).
Serve the veggies and salmon slathered with the dressing. Top with more herbs, some black pepper, and a squeeze of lemon.