Makes 4 servings
Prep time: 15-20 minutes for stovetop, 20-30 minutes in the oven (see below for oven method)
This is the most basic French preparation for leeks, and one of the most delicious. It's also the recipe that sold me on them forever.

1 bunch leeks (5 small or 3 large)
1 tablespoon butter, softened
1/4 cup white wine
1/2 cup chicken stock or water
Salt and pepper, to taste

Cut the root end off the leeks, as well as the dark green stem end, leaving just the white and light green portion. Split them lengthwise and remove the outer 2 layers. Wash thoroughly under running water, being careful to rinse between layers to remove any grit. Shake off the excess water.

Rub the bottom of a large, heavy-bottomed skillet with the softened butter, then lay the leeks, cut side down, in the pan. They should fit snugly in one layer across the pan. Pour the wine and chicken stock over the leeks, sprinkle with salt and a little pepper, then cover with waxed paper or parchment (which will keep the tops of the leeks moist), and bring the liquid to a boil.

Reduce the heat, cover the pan, and simmer over low heat for about 15 minutes. Use a small spatula or tongs to turn the leeks once, halfway through the cooking process. When cooked, the leeks should be completely tender and not stringy. Turn them over once more, so the outer layers are facing up. To test doneness, I usually just peel off one or two outer layers, the last to get cooked, and sample them (if they are the least bit tough, cook for another 5 minutes).

Remove pan from the heat and cool. If there are more than 2 tablespoons of juices left in the pan, remove the leeks to a serving platter and reduce the juices to 2 tablespoons. Whisk the juices into the Dijon Vinaigrette.

Pour the dressing over the leeks and let sit for at least 10 minutes. These leeks are wonderful served warm or cold, but I like them best at room temperature.

Dijon Vinaigrette

1 medium shallot, minced
1 tablespoon Dijon mustard
2 tablespoons wine or apple cider vinegar
Reserved leek pan juices
1/2 cup olive oilv Salt and pepper

Whisk together the shallot, mustard, vinegar, and pan juices in a small bowl. Slowly whisk in the olive oil, then season with salt and pepper.

Oven-braised Leeks: Alternatively, you can braise the leeks in a 350°F oven for 20 to 30 minutes in a buttered gratin dish (which, when cooled slightly and served atop a trivet, can go right to the table as a rustic-looking serving dish). Oven braising is actually easier: Cooked in this manner, the leeks do not need to be turned. Simply prepare the leeks as described above (placing them cut side down), and don't forget to cover them with parchment.