Make Sweetie Pie's potato salad using fully cooked potatoes, vinegar, mayonnaise, milk, onion and celery. Season it with spicy brown mustard, salt, pepper and parsley. Substitute or omit the mayonnaise and milk to reduce the fat content of this dish.
First cut 1.5 pounds of white potatoes and 1.5 pounds of sweet potatoes into 1-inch pieces. Boil the sweet potatoes and white potatoes in separate pots until they are tender. Use separate pots because sweet potatoes cook more quickly than white potatoes. Drain the potatoes, and combine them in a bowl. In another mixing bowl, combine 1/4 cup of red wine vinegar and 1 tablespoon of spicy brown mustard. Whisk together, and add 1 1/4 teaspoons of salt and 1/2 teaspoon of black pepper. Add this vinegar-mustard mixture to the hot potatoes, and stir gently, coating each piece evenly. Allow the potatoes to cool in a refrigerator. In another bowl, combine 1/2 cup of mayonnaise and 1/4 cup of milk. Chop two celery ribs and one small red onion. Mince 1/3 cup of fresh parsley, and stir it into the mayo-milk mixture. Slowly pour the mayo-milk mixture over the cooled potatoes. Serve this dish immediately, or cover and chill for future meals.