YIELD: 4 to 6 servings | PREP TIME: 15 minutes | CHILLING TIME: 2 hours • 2 English cucumbers (about 1½ pounds), halved lengthwise and roughly chopped • 1½ pounds green grapes, plus more for garnish • 1 avocado, peeled, pitted, and quartered • 1 small shallot, chopped...
