For Stewart's homemade mayo, you'll need one large egg yolk, one teaspoon of Dijon mustard, one teaspoon of fresh lemon juice, coarse salt, white pepper — I substituted it with black pepper, as it's what I had — and a cup of lightly flavored oil.
Stewart's recipe called for grapeseed, sunflower, or safflower oil, but I used vegetable oil — which is also mild in flavor — because I already had it in my kitchen.
The first step in making homemade mayo is mixing together the egg yolk, Dijon mustard, salt, pepper, and lemon juice.