Place washed cubed potatoes in a pot, cover with water and add salt. Bring the pot to a boil then simmer until tender, about 20 minutes. Drain and set aside.
Coat a saute pan with olive oil and bring to a medium high heat. Cook the bacon in the pan until crisp. Once crisp, place on a paper towel and crumble into pieces. Pour off fat from pan, leaving around 2 tablespoons in the pan. Add yellow and red onion and cook until soft and aromatic, around 5-7 min.
Wisk in the chicken stock, vinegar, mustard, paprika, pepper and add salt to taste. Stir until it thickens. Add in potatoes, and toss to coat.
Toss in or top with bacon, chives and parsley if using. Serve warm or at room temp.