Sweet and spicy, these preserves are as versatile as relish or olives. Serve them with nuts, spread on sandwiches, or add one or two grapes to a dry martini. Even though the grapes are ready to eat after 8 hours, they will continue to get more flavorful after a few days. Store up to 1 month in the fridge.
Heat all ingredients except grapes 3 to 5 minutes in small saucepan over medium heat, stirring until sugar is dissolved. Place grapes in glass jar, and pour vinegar mixture over grapes. Refrigerate overnight before serving.