1 large egg yolk, at room temperature 30 minutes
½ teaspoon Dijon mustard
¾ cup olive oil (or oil of choice), divided
1 teaspoon white-wine vinegar or apple cider vinegar
1 ½ teaspoons fresh lemon juice
Salt to taste
1. Whisk together yolk, mustard, and ¼ teaspoon salt until combined. Add about ¼ cup oil drop by drop, whisking
constantly until mixture starts to thicken.
2. Add vinegar and lemon juice, then remaining ½ cup oil in a very slow, thin stream, whisking constantly until well blended. If at any time it appears that oil is not incorporating into the mixture, stop adding oil and whisk vigorously until smooth, then continue adding oil.
3. Add salt to taste. Chill and cover until ready to use.
Note: The fresher the egg, the better it will incorporate into the mixture. Try using safflower, sunflower, or black truffle olive oil for subtle taste variations.