Radicchio Potato Salad with Mustard Dressing
6 servings

1 pound small yellow potatoes
1/4 medium sweet onion, thinly sliced
1/2 cup red wine vinegar, divided
Salt and black pepper
4 tablespoons olive oil
1 1/2 tablespoons coarse-ground mustard
1 head Royal Rose radicchio, cored and chopped
1/4 cup chopped parsley

Simmer potatoes covered in water until tender, about 15 minutes; drain, cut in halves or quarters and place in large bowl with onion. In small bowl whisk together 1/4 cup vinegar, oil, mustard and salt and pepper to taste; pour over potatoes and toss. Fold in radicchio and remaining vinegar, to taste. Season with salt and pepper, fold in parsley. Serve immediately, or cover and chill up to 6 hours.