• 3 pounds small boiling potatoes

For the Seasoning

• 2 tablespoons plus 1 1/2 teaspoons salt
• 1/4 cup good white wine
• 1/4 cup good-quality chicken stock

For the Vegetables

• 1 cup finely diced celery (4 stalks)
• 1/2 cup thinly sliced scallions (4 scallions), white and green parts
• 1/4 cup finely diced cornichons

For the Dressing

• 1 tablespoon Dijon mustard
• 1 tablespoon coarse mustard
• 3 tablespoons good-quality champagne vinegar or white-wine vinegar
• 1/2 teaspoon freshly ground pepper
• 1/2 cup good-quality olive oil

For the Garnish

• 1/4 cup freshly chopped dill