This classic French dish dresses up fresh leeks with a tangy Dijon mustard-based vinaigrette.
6 medium leeks, trimmed
2 tablespoons white wine vinegar
1 tablespoon Dijon mustard
1 tablespoon water
1/2 cup extra-virgin olive oil
Sea salt and fresh ground pepper
Fresh flat-leaf parsley and tarragon leaves, chopped
1. Bring a large pot of water to a boil over high heat, then salt it generously. Trim the root end of the leeks, leaving enough to hold the leaves together, and halve lengthwise. Rinse very well under running water to flush out any grit trapped between the leaves.
2. Add the leeks to the boiling water and cook until tender, 7 to 10 minutes. Transfer the leeks to a paper towel-lined plate to drain. Pat dry and lay on a serving platter.
3. Meanwhile, whisk the vinegar, mustard, water, and about ¾ teaspoon salt in a small bowl. Gradually whisk in the olive oil, starting with a few drops and then adding the rest in a steady stream to make a smooth, slightly thick dressing.
4. Drizzle the vinaigrette evenly over leeks, turn them to coat, and scatter the parsley and the tarragon, if using, over the top. Serve immediately or up to 2 hours later at room temperature.