"Always be prepared." It's not only the motto of the Boy Scouts of America, it's also the mantra of any great host. Eric Castro of San Diego's Polite Provisions suggests to achieve that goal via pre-made libations. His riff on the classic New Orleans cocktail, the Vieux Carré, can be kept chilled, stored in cleaned 750-ml. liquor bottles, and on hand for all impromptu soirées.