Leeks in Vinaigrette

• 4 large leeks, white and pale-green parts only, tough outer layer removed

Kosher salt

• 1 small shallot, finely chopped
• ½ garlic clove, finely grated
• 1 tablespoon Sherry vinegar or red wine vinegar
• 1 teaspoon Dijon mustard
• 1 teaspoon whole grain mustard
• ½ teaspoon finely chopped fresh thyme
• ¼ teaspoon sugar
• ¼ cup olive oil

Freshly ground black pepper

1. Trim root end of leeks (leave as intact as possible so they don’t break apart while cooking) and cook in a large pot of boiling salted water until meltingly tender (a paring knife should go all the way through with no resistance), 15–20 minutes. Transfer to paper towels to drain; let cool.
2. Whisk shallot, garlic, vinegar, Dijon and whole grain mustards, thyme, and sugar in a small bowl. Gradually whisk in oil and 1 Tbsp. water; season vinaigrette with salt and pepper.
3. Halve leeks lengthwise and arrange on a platter, cut side up; drizzle with vinaigrette and let sit at least 10 minutes before serving.
4. Do Ahead: Leeks can be made 1 day ahead. Cover and chill. Bring to room temperature before serving.