Should You Discard Leek Greens?

Leeks grow in the ground with the stalk covered. The part that does not see light stays white and tender, while the leaves above the soil turn dark green in the sun and become firm. The transition between them is pale green, with a texture close to the stalk. So the green part of a leek is not one single piece; it consists of two distinct parts. Chop the pale green part and add it to the dish with the white part; it adds color to the food. The dark green part has a different use. The dividing line is where the knife can cut through the leaf without force.

The dark green leaves are more fibrous than the stalk and have a sharper flavor. If chopped and added to leeks cooked in olive oil or to savory leek pastries, they stay tough even after cooking and leave stringy fibers when chewed. Their flavor does not disappear, though; it transfers to water during long cooking. For this reason, the dark green part is best treated as a flavoring, not served as part of the dish: add it to the pot, let it release its flavor, and remove it when the dish is done. The dried, yellowing outer leaves at the tips are not used at all; they are spoiled scraps and do not belong in stock either.

The first use is vegetable stock and broth. Add the dark green leaves in large pieces and cook them with the liquid; they give it an onion-like but milder flavor. The second use is in long-cooked soups: tie the leaves into a bundle with kitchen twine so you can remove them in one motion when the soup is done. The third use is in the oven; lay the leaves like a bed under meat or vegetables as they bake. They help keep the food from sticking to the pan and flavor the juices in it; remove them before serving.

If you use the green part, washing becomes even more important. Soil gets between the leaves, and grit collects most in the area where they open. Separate the dark green leaves from the stalk, split them lengthwise, and rinse under running water while separating the layers. Swish chopped pale green pieces in a wide bowl of water and lift them out by hand; the grit settles to the bottom, so do not pour the bowl into a strainer. If grit remains at the bottom of the bowl, repeat the process, because fine grit is hard to see in the water. Leave the washed leaves in a strainer to drain.

The dish determines how much of the green part to use. In cream or milk-based soups where color matters, dark green leaves cloud the color; use only the white and pale green parts and save the dark greens for stock. The pale green part adds color and flavor to leeks cooked in olive oil and to savory leek pastries. Straining out the dark greens is not a preference but a rule; even finely chopped, they remain stringy and spoil the texture of the dish. The pale green part also takes slightly longer to soften than the white stalk, so add it to the pot at the same time as the white part or before it.