How to Make Mayonnaise

Pull your ingredients out 20 to 30 minutes ahead so everything sits at room temperature. Cold yolk and cold oil refuse to emulsify cleanly, and a broken mayo is a sad thing. You'll need one large egg yolk, one teaspoon of Dijon mustard, one teaspoon of fresh lemon juice, one cup of grapeseed oil, salt, and a pinch of white pepper.

Grapeseed is Martha's pick because it's stable and flavorless, so the mayo tastes clean. Canola works too. Avoid extra-virgin olive oil for your first batch, since it can taste bitter when whipped this aggressively.

Crack one large egg and separate the yolk into your mixing bowl. Save the white for another use. An omelet, a meringue, a whiskey sour. One yolk handles a full cup of oil because of all that lecithin doing the emulsifying work.

Use the freshest egg you can find. The fresher the yolk, the more emulsifying power it carries.

Add one teaspoon of Dijon mustard and one teaspoon of fresh lemon juice to the yolk. This is your emulsifier base. The mustard adds a second emulsifier and brings flavor, while the lemon juice gives the acidic backbone that keeps mayo from tasting flat.

White wine vinegar works in place of lemon juice if that's what you have on hand. Same teaspoon, same result.

Whisk the yolk, mustard, and lemon juice together until the mixture looks smooth and slightly lighter in color. Just ten or fifteen seconds. You want everything fully combined before a single drop of oil goes in.

Anchor your bowl on the counter with a damp kitchen towel twisted into a ring. This keeps both hands free, one for the whisk and one for the oil, so the bowl cannot wobble when you start pouring.

Start adding the grapeseed oil one drop at a time, whisking constantly. Do not rush this. The first quarter cup is the danger zone and the make-or-break moment for your emulsion.

Once the mixture visibly thickens and turns pale and creamy, you can speed up to a thin steady stream. Keep whisking the whole way through. If your arm gets tired, that's the workout Martha promised. Stop when all one cup of oil is incorporated and the mayo looks silky and stiff enough to hold a soft peak.

Taste the mayo. Add about a quarter teaspoon of salt and a pinch of white pepper, then whisk to blend. Taste again. If it's flat, add a few more drops of lemon juice. If it feels too thick, whisk in a teaspoon of room-temperature water to loosen it.

White pepper keeps the mayo looking clean and white. Black pepper works fine too if that's what you have, you'll just see the specks.

If you own an immersion blender, you can skip the whisk entirely. Add the yolk, mustard, lemon juice, and full cup of oil to a tall narrow container like a two-cup measure. Drop the blender head all the way to the bottom and pulse without moving it for about ten seconds.

You'll hear the emulsion form. The sound changes as the mixture thickens. Slowly lift the blender as the mayo climbs up. Total time is under a minute, and it works every time.

Scrape the finished mayo into a clean glass jar with a tight lid. Refrigerate immediately. Homemade mayo keeps five to six days in the fridge because there are no preservatives, so make it in small batches and don't try to stretch a single yolk into a month's supply.

Use it on a BLT, fold it into chicken salad, thin it with olive oil for a salad dressing, stir in herbs for a sandwich spread, or grate in a garlic clove to turn it into aioli for fries and roasted potatoes.