Peel and finely chop 1/3 medium red onion and heat 1 tbsp olive oil over medium high heat in a medium skillet.
Add onions and 1/2 lb kielbasa sausage, sliced and turn heat down to medium and sauté until the sausage has turned a nice brown color, make sure that the onions do not burn.
Add 1 tbsp grainy mustard, 1 tsp dry mustard, 1 tsp celery seed, 1 tbsp sugar, 1/2 tsp kosher salt, freshly ground black pepper and deglaze with 1/3 cup cider vinegar stir until glossy then add 1/2 cup chicken or beef broth and reduce the liquid by 1/3.
Add potatoes to sausage mixture and fold the potatoes into the mixture gently, covering all the surfaces of the potato and allowing the juices to be absorbed.