1. Boil well washed, but not peeled, whole potatoes and onion. in a large pot of salted water until tender.Strain, discarding the onion, allow to cool until comfortable to handle. Cut into chucks, place into a bowl, covering it with a clean dry towel to keep the potatoes warm.
2. In a large pan, cook the bacon until crisp.Remove the bacon with slotted spoon and place them on a paper towel to drain. Add the red onions to the rendered bacon fat and cook until soft, 3 to 4 minutes. Carefully add the vinegar and mustard seeds, cook an additional 2 minutes. Whisk in the canola oil, carefully, salt and pepper to taste.
3. Gently toss the hot dressing with the potatoes, to coat. Fold in the parsley and green onion. If needed, salt and pepper to taste. Serve hot.

The pressure cooker method

Fry bacon in the pressure cooker until crisp, then remove and drain on paper towel and crumble. Reserve 1 Tbs of the drippings and wipe out the pressure cooker. In a small bowl, combine the sugar, vinegar, mustard and bacon drippings. Pour 1-3/4 cups water into the pressure cooker. Layer the potatoes, onions, all of the seasonings above, the sugar and vinegar mixture, and the crumbled bacon in the pressure cooker basket. Lower the basket into the pressure cooker. Lock the lid into place and cook for 2 minutes at 15psi. Release pressure using the natural release method or the auto release method, remove the lid, mix in the chopped parsley and serve.