Serves 8 to 10.
Hard-boil eggs. In a large bowl whisk together vinegar, oil, salt, and pepper. In a 5-quart kettle cover potatoes with salted cold water by 2 inches and simmer until just tender, 25 to 30 minutes. Drain potatoes in a colander. While potatoes are still warm, peel and cut into 3/4-inch pieces. Gently toss potatoes with dressing until combined well and let cool. (Potatoes will absorb most of dressing.)
Finely chop onion and bell peppers and diagonally cut celery into thin slices. Add vegetables to potatoes and toss well. Chop hard-boiled eggs and add to potatoes with mayonnaise and salt and pepper to taste. Gently stir salad until combined well. Chill salad, covered, at least 8 hours and up to 2 days. Serve salad chilled or at cool room temperature.