Bake the Potatoes:
Preheat the oven to 400°F (200°C). Wash and scrub the russet potatoes. Rub them with olive oil and sprinkle with salt. Place them directly on the oven rack and bake for about 45 minutes or until tender when pierced with a fork.

Prepare the Bacon:
While the potatoes are baking, cook the bacon in a skillet over medium heat until crispy. Drain on paper towels and crumble into small pieces.

Make the Dressing:
In a large bowl, mix together the mayonnaise, sour cream, and Dijon mustard (if using). Add salt and pepper to taste.

Chop the Potatoes:
Once the baked potatoes are cool enough to handle, cut them into bite-sized cubes, leaving the skin on.

Assemble the Salad:
In the large bowl with the dressing, add the chopped potatoes, crumbled bacon, shredded cheddar cheese, and chopped green onions. Gently toss to coat everything evenly.

Chill and Serve:
Cover the potato salad and refrigerate for at least 30 minutes before serving to let the flavors meld together.