Cut potatoes lengthwise in half. Trim and cut green beans and asparagus into 2-in. pieces. Place potatoes in a 6-qt. stockpot; add water to cover. Bring to a boil. Reduce heat; cook, uncovered, until tender, 10-15 minutes, adding green beans and asparagus during the last 4 minutes of cooking. Drain., Meanwhile, brush salmon with 1 tablespoon vinaigrette; sprinkle with salt and pepper. Place fish on oiled grill rack, skin side down. Grill, covered, over medium-high heat or broil 4 in. from heat until fish just begins to flake easily with a fork, 6-8 minutes., In a large bowl, combine potato mixture, arugula, tomatoes and chives. Drizzle with remaining vinaigrette; toss to coat. Serve with salmon.