Freshly squeezed citrus juice makes a terrific sustitute for vinegar. While lemon juice is most common, limes, tangerines, oranges, blood oranges, and even grapefruit have a place in your salad dressing.The acidity is lower, about 3% vs. 5% or higher for vinegar, but that makes it a good choice when you want the lower acidity or just a nice summer tangy flavor.