Place sliced potatoes in a large pot of water. Season with 2 tsp of salt. Bring to a boil over high heat. Lower heat and simmer until potatoes are fork tender. Drain potatoes and set aside.
While potatoes are cooking, in a large skillet cook bacon until crisp. Remove bacon to a paper towel lined plate to drain. Remove all but 2 TBS of bacon grease from skillet.
Place diced onion into pan with bacon grease and cook until onion has softened. Sprinkle flour and sugar over the cooked onion. Stir for 1 minute. Stir in water, vinegar, and seasonings. Simmer a few minutes until thickened. NOTE: Should be a smooth consistency, not pasty.
Remove from burner and stir in mayo or miracle whip dressing. Crumble in bacon and add the drained potatoes. Stir to coat the potatoes with the dressing. Garnish with fresh parsley or sliced green onions.