From Tapas by Penelope Casas
Makes about 1 1/4 cups
1 egg plus 1 yolk
1/4 teaspoon Dijon-style mustard
1 teaspoon kosher or sea salt
2 tablespoons fresh lemon juice
1 cup extra-virgin olive oil, or a mixture of olive and another vegetable oil
Place in the bowl of a blender or processor the whole egg, egg yolk, mustard, salt, and lemon juice. Blend for a few seconds. With the motor running, pour in the oil very gradually and continue beating until thickened and silky.