Dressing:

1/3 c. red wine vinegar
3 tbsp. Dijon mustard
1 c. extra-virgin olive oil
2 lb. small, red, new potatoes
3 scallions, thinly sliced
1/2 c. parsley (whole flat-leaf)

Cook potatoes in boiling, salted water about 20 minutes. Drain; cool and cut into quarters. Place potatoes in a large bowl. Pour the dressing over the potatoes. Season with salt and pepper. Toss carefully, using a large rubber spatula. Sprinkle with scallions and parsley. Toss to combine. Be sure to cover the potatoes with plenty of dressing as the potatoes absorb it quickly.