Place the potatoes in a large pot and cover them with water. Season the water with salt, if desired. Bring the water to a boil over high heat, then reduce heat to medium-low, cover and allow the potatoes to cook until tender - about 15-20 minutes.
Drain the potatoes into a colander and run them under cold water to cool.
In a large bowl, combine the sour cream and ranch dressing mix.
Add the potatoes, bacon, Cheddar, and green onions. Gently stir the mixture until it is well combined.
Cover and refrigerate at least two hours before serving.
Notes
If desired, you can use Russet potatoes in place of the red potatoes.
If you prefer a thinner dressing, you can add a touch of milk or buttermilk to reach your desired consistency.