How to Make It
Whisk together the garlic, mustard, vinegar, and yolk in a medium bowl. Stir together the oils and, while whisking constantly, slowly add to the bowl in a slow, steady stream until fully combined and thickened (the whisk should leave a trail). Whisk in the lemon juice, 1 to 2 tablespoons water, 1 teaspoon salt, and ¼ teaspoon pepper.
Refrigerate in an airtight container for up to 5 days.
Note: Because the egg in this recipe is not cooked, there is a risk of food-borne illness.