Put potatoes and 2 Tbsp Olive oil on sheet pan. Salt & Pepper to taste. Mix potatoes with the oil so they are lightly coated. Cook potatoes until cooked through about 35-40 minutes. Take out half way and turn potatoes over.
Heat a non stick skillet and add the bacon. Cook until bacon starts to crisp.
Add onion to pan and remaining 2 Tbsp olive oil. Season with S&P and red pepper flakes if using. Turn onions well and sweat until translucent. Add vinegar and stir well.
Remove potatoes from oven and smash them lightly with a potato masher.
Put potatoes into pan with onion & bacon mixture. Add parsley and stir well. Taste for seasoning.
Can be served warm or at room temperature.
Recipe by Cook Eat Run at https://cookeatrun.com/2014/08/03/smashed-potato-salad/