Cook 3 pounds sliced red potatoes in salted simmering water, about 8 minutes. Drain, then toss with 1/4 cup each chicken broth and white wine; let sit 5 minutes. Whisk 1/3 cup white wine vinegar, 3 tablespoons dijon mustard, 1 tablespoon poppy seeds and a pinch of sugar in a bowl; whisk in 1/2 cup olive oil, and salt and pepper. Toss with the potatoes, then chill 2 hours. Top with chives.