Horseradish-Mustard New Potatoes

Scrub potatoes; cut in halves or quarters. In a covered Dutch oven, cook potatoes in a small amount of boiling, lightly salted water about 10 minutes or until tender. Drain and return to pan. In medium saucepan, sauté onion in butter for 4 to 5 minutes or until tender. Stir in 1 tablespoon of flour and salt. Add chicken broth. Cook and stir until thickened and bubbly. In a small bowl, stir together sour cream, horseradish, mustard and remaining 1 tablespoon flour. Stir into broth mixture. Cook and stir until heated through. Pour sauce over potatoes; toss lightly to coat. Transfer to a serving bowl. Sprinkle with chives and cracked peppercorns.