This recipe is from Pascal Sauton, chef and owner of the French bistro Carafe. Sauton buys leeks with at least 12-15 inches of white tender shoots and very little green. If the leeks you’ve bought have less white and more green, you may need to use one or two more leeks. Use discarded green tops to make stock.

INGREDIENTS

1/4cup coarse sea salt
2 medium leeks
1 tbsp high-quality Dijon mustard (preferably Fallot brand)
1 tbsp sherry vinegar
1/3 cup canola oil
Fine sea salt and freshly ground black peppercorns to taste
1 hard-boiled egg
1 tbsp minced chives

(1) Boil 1 gallon water in a pot with the coarse sea salt.
(2) Peel off the first leaf or two of each leek; cut off roots and dark green tops (leaving 1-2 inches of the pale green portion). Wash leeks well under cold water. Slice each leek crosswise into 3-to-4-inch sections.
(3) Once the water has come to a boil, turn down heat to medium. Add the leeks and cook until just tender, about 10-15 minutes.
(4) Place the mustard and the vinegar in a small mixing bowl. Whisk the mixture vigorously, and add the canola oil slowly. Continue to whisk until a creamy emulsion has formed. Season with fine sea salt and freshly ground black peppercorns to taste. Set aside.
(5) When they are tender, drain the leeks, then place them in a bowl of ice water to cool. Let sit for 5 minutes. Drain the leeks again, then gently squeeze them to allow residual water to escape. Pat dry with paper towels.