Steamed Leeks with Truffle Dressing

Lift the lid off a pot of steaming leeks and the first thing that reaches you is a soft, sweet smell, somewhere between onion and cut grass, with none of the sharpness raw onion has. Then comes a second smell, deeper and earthier, from a few drops of truffle oil stirred into a mustard vinaigrette and spooned over the warm leeks. That meeting of mild steam and a dark, savory dressing is the whole idea behind these steamed leeks with truffle dressing.

What is documented and what is not: leeks steamed and served with a vinaigrette is a classic, well-documented preparation, and the steaming times and doneness test here follow a published steamed-leek method I found. Adding truffle oil is my own variation, and I have not tested this exact dressing in a test kitchen. The quantities of the dressing are my adaptation, so taste and adjust.

Ingredients

Leeks

• 4 medium leeks, about 700 g (1 1/2 lb) before trimming
• Water for the steamer pot

Truffle Dressing

• 3 tablespoons olive oil (45 ml)
• 1 tablespoon cider vinegar (15 ml)
• 1 tablespoon lemon juice (15 ml)
• 1 tablespoon Dijon mustard (15 g)
• 1/4 teaspoon sugar
• 1/2 teaspoon fine salt
• 1/8 teaspoon black pepper
• 1 teaspoon truffle oil (5 ml), added last

To Finish

• 2 tablespoons chopped chives
• Flaky salt, to taste

The documented steamed-leek method I followed uses cider vinegar, Dijon, salt, pepper and a little sugar whisked with olive oil until it emulsifies. I kept that backbone and added lemon juice for brightness and truffle oil for depth. If you have no lemon, use another tablespoon of cider vinegar and a pinch less salt.

Getting the Grit Out Without Losing the Layers

Leeks grow with soil trapped between their layers, and a quick rinse under the tap does not reach it. The method I followed says to trim, then soak and rinse the leeks thoroughly. Here is how I handle it, which is my own approach rather than part of that source.

Cut off the dark green tops and the dry root hairs, but leave the white base attached, since it holds the layers together. Slice each leek in half crosswise so the pieces fit your steamer. Make a shallow lengthwise cut through the outer layers, then fan them open under running water and let the water carry the dirt out. When no grit settles in the bottom of a bowl of water, they are clean.

Instructions

1. Clean and trim the leeks. Prepare them as described above and drain them well. Lay them in a single layer in a steamer basket.
2. Bring the water to a boil. Pour about 2.5 cm (1 inch) of water into a pot and set it over high heat for 4 to 5 minutes, until it is boiling vigorously and the steam is steady. The water must stay below the basket.
3. Steam the leeks. Set the basket over the pot, cover tightly, and steam for about 10 minutes for slim leeks, 3/4 inch (2 cm) thick, or about 12 minutes for thicker ones, 1 1/4 inches (3 cm) across. The inside of the lid will be wet and the smell of the steam will turn sweet.
4. Test the thickest part. Slide a knife tip into the thickest part of a leek. It is done when it meets no resistance. If it grips the blade, steam 2 minutes more and test again.
5. Make the dressing while they steam. In a small bowl, whisk the vinegar, lemon juice, Dijon, sugar, salt and pepper until smooth. Add the olive oil in a slow stream, whisking until the dressing thickens slightly and looks glossy and creamy rather than separated.
6. Add the truffle oil. Stir in the truffle oil last, then taste on a corner of leek, not on its own. The dressing should taste a touch sharper than you want, because the mild leeks will soften it.
7. Drain and dress. Lift the leeks out and let the steam clear for about 1 minute so they do not water down the dressing. Lay them on a platter, spoon the dressing over, and finish with chives and a pinch of flaky salt.

Steamed Leeks with Truffle Dressing: How to Know They Are Done

Steam trimmed leeks for about 10 minutes if they are 3/4 inch (2 cm) thick, or 12 minutes at 1 1/4 inches (3 cm). They are done when a knife tip slides into the thickest part with no resistance. Pull them as soon as that happens, because they keep softening while they cool.

Time is only a guide. Leek thickness varies a lot, so the knife test is what counts. For comparison, another published leek method simmers the leeks in salted water for 15 to 20 minutes and judges them by whether the layers separate when lifted out. The source I followed says steaming gives a sweeter, more onion-like taste than boiling. I cannot prove that difference myself, but I can say steaming is simpler to control, since the leeks never sit in water that can leave them waterlogged.

Using Truffle Oil Without Overdoing It

Truffle oil is not what the name suggests. Many bottles contain a manufactured aroma compound rather than real truffle, and the compound used most often can legally be labeled “truffle aroma” or “truffle flavor.” Some bottles do hold a piece of truffle, which may come from any of several hundred species, not necessarily a prized one. Read the label and decide what you are buying.

Truffle oil is generally treated as a finishing oil, used on fries, pasta, pizza and purées, so I add it to the cold dressing rather than the steam pot. A teaspoon is a starting point. The aroma should read as a background note under the mustard and lemon. If you can smell nothing else, you have used too much.

Where Steamed Leeks Go Wrong

• Grit in the dish. The most unforgiving mistake. Fan the layers open and rinse them until the water runs clear.
• Leeks sitting in water. If the water touches the basket, the leeks boil in part and turn limp. Keep the water level low.
• Skipping the knife test. Under-steamed leeks are stringy, while over-steamed leeks collapse when lifted.
• Dressing wet leeks. Surface water thins the dressing and leaves a pool on the plate. Let the steam clear for a minute before spooning.
• Too much truffle oil. It can swamp the leeks. Add a little, taste, and stop.

Serving, Variations and Storage

The steamed-leek source says to serve warm or chilled, and both work. Warm leeks take the dressing in more readily. Chilled leeks are firmer and suit a make-ahead plate. Serve them next to roast chicken, fish, or a soft-boiled egg on toast.

Variations

• Crunch: Scatter toasted hazelnuts or fried breadcrumbs over the top.
• Without truffle oil: Use extra olive oil and a pinch of dried thyme for an ordinary leek vinaigrette.
• Sharper dressing: Use 2 tablespoons of lemon juice and no vinegar.

Storage

Keep undressed cooked leeks and the dressing in separate covered containers in the refrigerator. One published leek recipe says cooked leeks keep up to 3 days ahead and its vinaigrette up to 3 days in the fridge. That source uses a different dressing, so treat those numbers as a guide, not a guarantee. Dress the leeks only when you serve them.

Nutrition (Estimate)

These are rough estimates for one serving, not lab-tested values. I did not calculate them from a nutrition database, and they will change with the size of the leeks and the amount of oil you use.

Frequently Asked Questions

Should I use the green part of the leek?

Use the white and pale green parts. The dark green tops are tougher, so I trim them off for steaming. They are better saved for stock.

Can I steam the leeks without a steamer basket?

I have not tested this, but a heatproof rack or a colander set over a pot with a tight lid should work, as long as the water stays below the leeks. Use the knife test to judge time.

Is the truffle oil necessary?

No. Without it, the dressing is a plain mustard vinaigrette, which is the traditional way to serve steamed leeks. The truffle oil adds an earthy note, nothing more.

A Plain Vegetable, Treated Slowly

Leeks are an easy vegetable to overlook, usually sliced into a soup base and forgotten. Steamed whole and dressed with care, they become the center of the plate. There is something calming in the method: a pot, a lid, ten minutes of steam, a small bowl of dressing. The dish asks little and rewards attention to a few details, which is a good reason to keep it in rotation. Serve it when you want something quiet and well made.