2 tablespoons chopped chives
Flaky salt, to taste
Instructions:
Trim and clean the leeks: cut off the dark green tops and root hairs, leave the white base attached, halve crosswise, fan the layers open under running water, and drain. Lay them in a single layer in a steamer basket.
Pour about 2.5 cm (1 inch) of water into a pot and bring it to a vigorous boil over high heat, 4 to 5 minutes. The water must stay below the basket.
Set the basket over the pot, cover tightly, and steam 10 minutes for leeks 2 cm (3/4 inch) thick or 12 minutes for leeks 3 cm (1 1/4 inches) thick.
Slide a knife tip into the thickest part of a leek. It is done when it meets no resistance. If not, steam 2 minutes more and test again.
While they steam, whisk the vinegar, lemon juice, Dijon, sugar, salt and pepper in a bowl. Add the olive oil in a slow stream, whisking until glossy and slightly thick.
Stir in the truffle oil last and taste on a corner of leek. Adjust the seasoning.
Lift the leeks out and let the steam clear for about 1 minute. Lay them on a platter, spoon the dressing over, and finish with chives and flaky salt.