- 2 pounds small red and Yukon gold potatoes, halved (quartered if large)
- 2 tablespoons coarse salt
- 2 tablespoons red wine vinegar
- 1 tablespoon Dijon mustard
- 1/3 cup extra-virgin olive oil
- 1 small red onion, cut into 1/4 inch dice
- 5 cornichons, rinsed and sliced into thin rounds
- 2 tablespoons capers, rinsed and coarsely chopped
- 2 tablespoons coarsely chopped fresh flat-leaf parsley
- 1 1/2 teaspoons coarse salt
- 1/4 teaspoon freshly ground pepper
- Cover potatoes with water in a medium saucepan. Add 2 tablespoons salt. Bring to a boil; reduce heat, and simmer until tender, 7 to 9 minutes. Drain potatoes, reserving 1 tablespoon cooking water. Let potatoes cool slightly.
- Make the vinaigrette: Whisk together vinegar, mustard, and reserved cooking water in a small bowl. Gradually add oil, whisking until emulsified. Transfer potatoes to a medium bowl, and drizzle with vinaigrette. Add onion, cornichons, capers, parsley, remaining 1 1/2 teaspoons salt, and the pepper. Using a large spatula, gently stir to combine.