From the LA Times, which they further use in several recipes.
Ingredients
2 large egg yolks, at room temperature
1 tablespoon white wine vinegar
1/2 teaspoon Dijon mustard
1 cup canola oil
Salt to taste
Instructions
1. Whisk together the egg yolks, vinegar and mustard in a medium bowl until pale in color. Add the oil drop by drop, whisking constantly, until the mixture begins to thicken.
2. Continue whisking in the oil more steadily now, until all the oil is incorporated. Important note: If the mixture begins to break, you can add a few drops of water to bring it back together. Season with salt to taste. Store in the refrigerator until ready to use; keeps for two days. Makes 3 1/3 cups.