Prepare the potatoes. Wash the red potatoes thoroughly, leaving the skins on. Bring a large pot of lightly salted water to a boil.
Boil until tender. Add the whole potatoes to the boiling water and cook for approximately 15 to 20 minutes, or until tender when pierced with a fork.
Cool and chop. Drain the potatoes and rinse them under cold running water to help cool them. Cut the potatoes into approximately 1-inch cubes.
Chill the potatoes. Transfer the cubed potatoes to a large serving bowl. Cover and refrigerate until completely chilled.
Prepare the ranch dressing. In a small mixing bowl, combine the dry ranch dressing mix, mayonnaise, and chopped green onion. Stir until smooth and evenly mixed.
Refrigerate the dressing. Cover the ranch dressing mixture and refrigerate for at least 1 hour to allow the flavors to blend.
Cook the bacon. Arrange the bacon slices on a microwave-safe plate lined with paper towels, with additional paper towels over the bacon to catch splatters. Microwave until crisp, approximately 15 minutes, depending on your microwave's power. Cook in batches if necessary.
Cool and crumble the bacon. Carefully remove the bacon from the microwave and let it cool. Once cool enough to handle, crumble it into bite-sized pieces.
Combine potatoes and dressing. Remove the chilled potatoes and ranch dressing from the refrigerator. Pour the dressing over the potatoes and gently toss until evenly coated.
Add the bacon. Sprinkle the crumbled bacon into the salad and stir briefly to distribute it without breaking apart the potato pieces.
Serve. Transfer the finished ranch potato salad to a serving dish and serve chilled.
