Heat a large pot of generously salted water over high heat.
Cut baby potatoes in half (or into bite sized chunks if using larger potatoes) and add to the boiling water. Turn heat down to medium-low, cover with the pot lid, leaving it slightly ajar to allow steam to escape. Potatoes are finished when they are easily pierced with a fork. You can also cook uncovered; it may take a couple minutes longer. *Watch closely because the water can quickly boil over.
Drain and spread potatoes in an even layer on a flat surface like a cookie sheet or cutting board. Sprinkle evenly with a teaspoon of salt. Cool to room temperature (can be done in the fridge). Do not leave sitting for too long as the starches in the potatoes can get gummy.
In a small bowl, stir together mayo, sour cream, Dijon mustard, apple cider vinegar, garlic powder, parsley and salt and pepper.
Once potatoes are cooled, stir them together in a large bowl with the mayo mixture until coated. Stir in bacon, blue cheese and green onions (saving a little of the last few ingredients for garnish if desired).
Garnish salad with additional blue cheese and green onions, if desired. Chill until ready to serve.
Store in a tightly sealed container for up to 4-5 days.