Combine the olive oil and vegetable oil in a liquid measuring cup or bowl; set aside. Whisk the egg yolk, vinegar and 1/2 teaspoon salt in a small nonreactive bowl.
Set the bowl with the yolk mixture on a damp kitchen towel to steady it. Drizzle in the oil mixture very slowly, whisking constantly. (The mixture will begin to thicken after about half of the oil is added; if at any point the oil is not incorporating, stop drizzling and whisk until smooth.) Refrigerate in an airtight container for up to 4 days.
Puree 1/2 cup each fresh parsley, olive oil and vegetable oil, 1/4 cup fresh cilantro, 1 tablespoon red wine vinegar, 1 chopped garlic clove, 1/2 teaspoon kosher salt and 1/4 teaspoon each pepper and ground cumin until smooth. Make homemade mayonnaise (above) with the herb oil instead of the olive oil mixture.
Make homemade mayonnaise (above), stirring 1/8 teaspoon turmeric into the olive oil mixture and substituting champagne vinegar for the white vinegar. Whisk 2 tablespoons whole-grain mustard and 1 teaspoon honey into the finished mayonnaise. Season with salt.
Spicy Sesame-Ginger Mayonnaise
Mix 1 cup vegetable oil with 2 tablespoons sesame oil. Make homemade mayonnaise (above) with the sesame oil mixture instead of the olive oil mixture; substitute rice vinegar for the white vinegar. Whisk 1 tablespoon grated ginger, 1 1/2 teaspoons Sriracha and 1/2 teaspoon each sesame seeds and brown sugar into the finished mayonnaise. Season with salt.
Photograph by Paul Sirisalee
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.