Scrub the potatoes and prick them with a fork a few times. Microwave them on high for about 8 minutes until they are cooked. 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.Mix flour and ½ cup milk together and 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. Whisk in sour cream, salt and pepper. Set aside.Scoop the potato out of the skins, and mash it 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.