Arugula with Roasted Salmon and New Potatoes

Preheat oven to 450 degrees. On a large rimmed baking sheet, toss potatoes with 1 tablespoon oil; season with salt and pepper. Roast 10 minutes. Toss potatoes, and push to sides of sheet; place salmon in center, and season with salt and pepper. Roast until potatoes are tender and salmon is opaque throughout, 10 to 15 minutes. Transfer salmon to a plate; break into large pieces with a fork. While salmon is cooking, whisk together vinegar, mustard, chives, and remaining 2 tablespoons oil in a large bowl; season with salt and pepper. Add arugula and potatoes; toss to combine. Top salad with salmon pieces.