Beautiful with cold shellfish, fish, vegetables, and cold poached meats. Use a ceramic, glass, or stainless-steel bowl—aluminum or copper will react with the acid and affect the color and even the flavor of the sauce.
Whisk together in a medium bowl until smooth and light:
      2 large egg yolks
      1 to 2 tablespoons fresh lemon juice or white wine vinegar
      1/4 teaspoon salt
      Pinch ground white pepper
Whisk in by drops until the mixture starts to thicken and stiffen:
      1 cup vegetable oil, at room temperature
As the sauce begins to thicken—when about one-third has been added—whisk in the oil more steadily, making sure each addition is thoroughly blended before adding the next. Should the oil stop being absorbed, whisk vigorously before adding more. Stir in:
      2 to 3 tablespoons minced fresh herbs, such as tarragon, basil, chervil, chives, parsley, and oregano
      Up to 1 1/2 teaspoons Dijon mustard (optional)
      Salt and ground black pepper to taste
Serve immediately or refrigerate in a covered jar for 1 to 2 days.