Place potatoes in a Dutch oven; cover with water. Bring to a boil. Reduce heat; cover and simmer for 25-30 minutes or until tender. Drain and cool., In a large skillet, cook bacon over medium heat until crisp; using a slotted spoon, remove to paper towels. Drain, reserving 4 tablespoons drippings. In the drippings, saute onion until tender. , Stir in the flour, salt, celery seed and pepper until blended. Gradually add the sugar, vinegar and water. Bring to a boil over medium-high heat; cook and stir for 2 minutes or until thickened. , Cut potatoes into 1/4-in. slices. Add potatoes and bacon to the skillet; cook and stir gently over low heat until heated through. Sprinkle with parsley. Serve warm.