Leeks are the kitchen's unsung heroes. Their subtle, delicate flavors are essential to comforting soups, stews and braises.

But it's rare that the leek stands alone in a dish. This tall, slender vegetable, whose vibrant green stalk fades to a white whiskered root, is a very elegant onion. Unlike its bossy, brassy onion cousin, leeks are lower in sugar and so generally less sweet. Leeks will not caramelize when roasted or sautéed, and they don't like high heat.

Instead, leeks are best cooked slowly with a gentle hand over a low flame. You cannot rescue a pan of over-browned leeks the way you can with onions. (The gigantic elephant garlic is actually a leek, not true garlic, and like the leek, very mild.)

Leeks coming out of California are in their prime right now. They are a good bet until our local ramps (wild leeks) arrive in late spring. Native to the Mediterranean region, leeks are essential to classic European cuisine, a staple in France. Think vichyssoise and quiche.

In Ireland, leeks meld beautifully with potatoes and are essential to the iconic dish called colcannon — cooked potatoes, cabbage and lots of leeks, sautéed in oodles of butter to a fine fare-thee-well.

When choosing leeks, look for plump, firm bulbs with dark green leaves that are crisp, firm and blemish-free. Check to be sure the roots are light in color and still pliable. Avoid darkened, dried roots and wrinkled, wilted leaves. Once you get them home, keep leeks in a plastic bag in the refrigerator for up to five days.

Because leeks grow mostly underground, grit can lodge between the layers of their leaves. Before cooking, remove the whiskers, slice them in half, and wash them thoroughly under cold running water. If the outer layer is wilted or discolored, pull it off and discard. Most recipes call for the white and lighter green parts. The darker parts of the stalk can be tough and bitter, though some cooks like to use them in stock.

This simple dish of roasted leeks is deceptively simple. Most recipes call for blanching the leeks first to soften them before they roast. While that speeds the process, the same thing can be accomplished by baking them in a covered dish, then browning them uncovered. It takes a little longer, but saves some of the fuss.

Roasted leeks are delicious as a side to roast chicken or pork. Leftovers are terrific on pizza or tossed with pasta and a little cheese.

If you're feeling Irish, sizzle them in a big skillet with mashed potatoes and shredded cabbage into comforting colcannon. It's the perfect match to St. Paddy's Day corned beef.

Beth Dooley is the author of "In Winter's Kitchen." Find her at bethdooleyskitchen.com.