One of the great pleasures of cooking is being surprised by an ingredient you thought you knew completely. You read a recipe, or an idea pops into your head for handling it a completely different way, and a whole new world of possibilities opens: the cook's eureka moment.

Like many people, I viewed leeks as an oniony flavoring for dishes, or as leeks vinaigrette or as a cooked garnish in a stew or sauce; I loved them rubbed with olive oil and roasted in a foil package. Then I bought a bunch of leeks at the farmers' market and it occurred to me to julienne them - cut them into thin strips - to treat them like noodles. Since leeks are long and narrow, with internal layers, they naturally take to julienning with very little work.

I steam them and then toss with creme fraiche or heavy cream to make a silky, noodley side dish or bed for grilled or roasted fish. Sometimes I add a few leaves of tarragon, chervil or thyme, slivers of lemon zest or a few scrapings of nutmeg. A teaspoon of roasted hazelnut or walnut oil takes the leeks into a whole other realm: "luxurious" is the only way to describe them.

Carrying the leek noodle idea a step further, I toss steamed, julienned leeks with beurre noir - butter that is slowly "toasted" in a saucepan until it turns deep brown, with the aroma of roasted hazelnuts. A splash of vinegar contributes a slight sweetness and acidity.

Leeks tossed with beurre noir make a lovely side dish, or even a first course (you can pair them with other cooked, sliced and warmed winter vegetables such as beets, new potatoes or Jerusalem artichokes). The addition of some fresh goat cheese, warmed briefly in the oven, or a few thin slices of prosciutto di Parma, makes for a perfect lunch.

Since the leek noodles are like pasta, it seems natural to pair them with real pasta. Simply make the leek noodles with creme fraiche, toss them with cooked linguine and a few tablespoons of cooking water to help the sauce coat, and finish with grated Parmigiano and freshly ground pepper. Or try a more elaborate version with pancetta and goat cheese.

Leftover leek noodles are terrific warmed and layered into macaroni and cheese, or used as an omelet filling. Sprinkled with grated Parmigiano Reggiano and baked until the top is brown, they make a lovely gratin.

Leek 'Noodles' With Beurre Noir

Serves 4

10 medium leeks, about 21/2 pounds

1/4 teaspoon salt

2 or 3 medium beets or new

potatoes, cooked and peeled, sliced into disks or half-moons (optional)

2 tablespoons unsalted butter

2 tablespoons balsamic

or sherry vinegar

Freshly ground pepper to taste

1. Trim the roots and tough green tops from the leeks, leaving about 1 inch of pale green.

2. Slice each leek lengthwise into quarters; you will see that each section consists of neatly stacked layers of leek. Press each section gently against the work surface, and using a thin sharp knife, slice lengthwise into 1/8-inch thick slices. (Or, if it's easier to manage, slice each leek quarter lengthwise in halves or thirds to make thin strips - they don't need to be perfect).

3. Rinse the leeks in several changes of cold water to remove any grit. Drain the leeks.

4. In a medium saucepan with a steamer basket, bring 1 inch of water to a boil. Add the leeks, toss with the salt, cover and steam until tender, about 5 minutes. Transfer the leeks to a medium bowl and cover. If serving them with beets or potatoes, add the vegetables to the steamer, cover and steam until warmed through, about 2 to 3 minutes.

5. In a small heavy skillet, cook the butter over moderate heat until golden brown and smells like roasted nuts, about 2 minutes. Turn off the heat and add the vinegar. The butter will sputter and darken in color. Add half the brown butter to the leeks and toss, adding salt and pepper to taste. Place a mound of leeks on each of 4 plates; arrange the beets or potatoes around the leeks. Spoon the remaining brown butter over the vegetables.