- 2 pounds small red potatoes, unpeeled, scrubbed, and cut into 1/4-inch-thick slices
- 2 Tablespoons kosher salt
- 1 medium clove garlic
- 1 1/2 tablespoons champagne vinegar or white wine vinegar
- 2 teaspoons Dijon mustard
- 1/4 cup olive oil
- 1/2 teaspoon ground black pepper
- 3 Spring onions sliced thin
- 2 radishes thinly sliced (about 1/3 cup)
- 1/4 cup capers
- 1/4 cup cornichons (small sour pickles), thinly sliced
1. Place potatoes, 6 cups cold water, and salt in large saucepan; bring to boil over high heat, then reduce heat to medium. Simmer potatoes, uncovered, until tender but still firm (thin-bladed paring knife can be slipped into and out of center of potato slice with no resistance), about 5 minutes. Drain potatoes, reserving 1/4 cup cooking water. Arrange hot potatoes close together in single layer on rimmed baking sheet or lay gently in a large bowl.
2. Press garlic through garlic press or mince by hand. Whisk garlic, reserved potato cooking water, vinegar, mustard, oil, and pepper in small bowl until combined. Drizzle dressing evenly over warm potatoes; let stand 10 minutes.
3. Transfer potatoes to large attractive serving bowl; add onion, radishes, capers, and cornichons; mix gently with rubber spatula to combine. Serve immediately it is wonderful warm but can also be served cold if making ahead.