Place the turnips in a 2-gallon ceramic jar. In a mixing bowl, stir together the water, vinegar, sugar, salt and crushed grapes and pour over turnips. Cover and refrigerate for 48 hours.
Two days later: In a 12 to 14-inch saute pan, heat the olive oil until smoking over medium heat. Add onions and garlic and cook until softened, about 8 minutes. Add flour and caraway and stir through. Drain turnips and add to pan. Cook until very soft, careful not to break the turnips, about 1 hour. Serve with grilled sausages or pork shank (stinco).