In a medium bowl, combine 3 tablespoons sherry vinegar or white wine vinegar and 1 shallot, finely chopped. Let stand for 15 minutes. Whisk in 1 tablespoon Dijon mustard, 1 tablespoon honey, 1/8 teaspoon salt and 1/8 teaspoon black pepper. While slowing adding 1/4 cup walnut oil in a steady stream, whisk until mixture is thickened. Makes about 1/2 cup.