Mix the Ingredients: In a bowl, combine 2 tablespoons of mayonnaise, 1 teaspoon of Dijon mustard, 1 teaspoon of old-fashioned mustard, 1 grated garlic clove, and 1 tablespoon of finely chopped chives. Season with salt to taste.
Refrigerate: Transfer the sauce to the fridge until needed. This quantity is enough for 3-4 burgers.