Place potatoes in a large pot and cover with water. Bring to a boil, generously salt the water, and boil the potatoes until tender, approximately 30 to 40 minutes. Drain and let stand until cool enough to handle. Peel potatoes, if desired, and cut into 1-inch chunks. Place cut potatoes in a large bowl. Sprinkle parsley and green onions over potatoes. Make the sauce by mixing the rest of the ingredients together in another bowl; then pour sauce over the potatoes. Stir well. Let stand all day, or at least for 4 hours, stirring every hour. Do not refrigerate. Serve at room temperature.