Scrub and dry the potatoes, and prick them all over with a fork. Place the potatoes on a plate, and microwave them on high for 13 minutes. The potatoes should be tender. Cut them in half, and set aside.
While the potatoes are cooking, heat the oil in a saucepan over medium-high heat. Add onion, and sauté for 3 minutes. Add broth.
In a small bowl, combine flour and ½ cup milk. Add the mixture to the pan with 1½ cups milk. Bring to a boil, stirring frequently. Cook for 1 minute.
Remove the pan from the heat. Stir in sour cream, salt and pepper. Set aside.
Place a paper towel on a microwave-safe plate. Arrange your bacon halves on the paper towel, and cover them with a second paper towel. Microwave on high for 4 minutes. Crumble bacon. Set aside.
Scoop the potato pulp out of the skins, and mash the pulp into the soup (at this point I pureed it with my emsulsion blender to get it even smoother) . Discard skins.
Garnish each serving of soup with cheese, green onions and crumbled bacon. Serve immediately.