- 3 tablespoons Dijon mustard
- 2 tablespoons red wine vinegar
- ½ teaspoon sea salt, preferably gray salt
- ½ cup extra virgin olive oil
- Freshly ground black pepper
- 2 pounds Yukon Gold potatoes, skin on, cut into 1-inch chunks
- 2 cups diced tomato, skin on, including seeds and juice
- ½ cup finely minced red onion
- 2 teaspoons finely minced fresh tarragon
- Make the vinaigrette: In a bowl, whisk together the mustard, vinegar, and salt. Whisk in the olive oil gradually, then season with pepper.
- Put the potatoes in a large pot of cold, well-salted water to cover. Bring to a boil, adjust the heat to maintain a gentle simmer, and cook until tender when pierced, about 15 minutes. Drain well and transfer to a large bowl to cool slightly.
- Add some of the vinaigrette to the potatoes and toss; you may not need it all. Add the tomato, onion, and tarragon and toss again. Taste and adjust the seasoning. The salad will probably need more salt.