Peel skin from the squash and cut it in half. Carefully remove the seeds and stringy matter. Cut the squash into medium dice from the center. In a saute pan, put the balsamic vinegar and water, salt and pepper, and heat. Add the squash and cook for just a few minutes; it should remain firm. Remove the squash and liquid from the heat and put into a separate bowl. Cool completely. Add the chopped mint and serve as a garnish or side dish.