Citrus is dear to Michael Cecconi, mixologist at New York’s Back Forty (he also worked at the Savoy and teaches at the Institute of Culinary Education). His advice is to use up every last bit of your lemons and limes. The day before a party, zest some citrus and let the zest sit in a Mason jar with an alcohol like bourbon or tequila. The next day, juice the fruit and add it and the zest to your liquor. Then enjoy.