Make in a jar: add pesto to a jar and add olive oil bit by bit to loosen if needed, then add the remainder of the oil and the vinegar. Shake together. Taste and adjust vinegar if needed and add salt and pepper.
In a blender: Add pesto to the blender and with the motor running, drizzle in the olive oil to emulsify. Add vinegar. Taste and adjust vinegar if needed and add salt and pepper.
Keep in mind your pesto can be stronger and more flavorful or mild depending on what you use. It can also be thicker or thinner. Be prepared to adjust the amount of pesto, oil and/or vinegar to find your balance.
Keywords: Italian, Pesto, Salad, Salad Dressings, Vinaigrette