- ¼ teaspoon ground black pepper, plusmore to taste
- ¾ teaspoon fine sea salt, plus more to taste
- 2 tablespoons extra-virgin olive oil
- 2 tablespoons finely chopped fresh dill
- ¼ cup finely chopped cornichons (about 8 cornichons)
- ½ cup finely chopped red onion
- 2 teaspoons whole-grain mustard
- 2 tablespoons white wine vinegar
- ½ – ¾ cup chicken stock, as needed, divided
- 2 pounds yellow or gold fingerling potatoes
- Place potatoes in a large saucepan; add cold water to cover by at least 1 1/2 inches. Bring to a boil over medium-high. Reduce heat to medium; simmer, stirring occasionally, until potatoes are tender, about 14 minutes. Drain and let stand until just cool enough to handle, 5 to 10 minutes. Peel potatoes using a small, sharp knife. Slice into 1/2-inch-thick rounds, and place in a shallow bowl.
- Place 1/2 cup chicken stock in a small microwavable bowl. Microwave on high until hot, about 30 seconds. Add vinegar and mustard; stir to combine. Pour over potatoes in bowl; toss gently to combine. Set aside to let soak at room temperature, stirring occasionally, 1 hour.
- If potatoes have absorbed most of the stock mixture after 1 hour, stir in remaining 1/4 cup chicken stock. Add onion, cornichons, dill, oil, salt, and pepper; toss gently to combine. Let stand at room temperature, stirring occasionally, at least 2 hours or up to 4 hours. Season with additional salt and pepper to taste.