Bartenders borrow from chefs all the time. It may have started when someone stole a pickled onion from the salad station to float in a martini, but these days, beets, Thai peppers, and even mushrooms are being tossed into cocktail shakers. Recently, Duggan McDonnell of Cantina took another idea from the kitchen and started offering a liquid amuse-bouche—that little bite served to both whet and temporarily sate diners’ appetites before the meal begins. When he’s faced with a thirsty horde six feet deep and a list of labor-intensive cocktails to mix, McDonnell sends a bartender into the crowd with shots of his Caribbean sangria. Made from ingredients that sound like they were raided from the hold of a pirate ship, the drink includes hibiscus syrup, claret, the traditional Barbados spirit falernum (flavored with lime, cloves, and almonds), and a generous dose of Jamaican black rum. One of these down the hatch can make the wait for a proper drink a little more bearable, and, from the bartender’s point of view, it just might prevent a mutiny. Cantina: 580 Sutter St., S.F., 415-398-0195, cantinasf.com