A good, puckery vinaigrette has a ratio behind it: three parts oil to one part acid. Acid can take the form of vinegar or citrus juice. "Once you understand that, you got this," says chef Hugh Acheson. "Add whatever you want. Go flavor-crazy. Shake that jar. Work those forearms." If you make too much, it will keep in the fridge for seven to 10 days in a sealed container.