Cover potatoes with salted cold water by 2 inches in a 3-quart saucepan and simmer uncovered until just tender, 15 to 25 minutes, depending on size of potatoes. Drain in a colander and cool slightly.
While potatoes are simmering, whisk together vinegar and salt in a large bowl until salt is dissolved.
When potatoes are just cool enough to handle, peel potatoes and cut into 1-inch pieces, adding to vinegar mixture as cut, and toss gently with rubber spatula to combine. Let cool to room temperature, then add remaining ingredients and salt and pepper to taste and stir gently to combine. Serve at room temperature or chilled.