Combine diced potatoes, carrots, celery and onions with chicken broth in a pot season with salt and pepper.
Cover pot and bring to a boil, once it reaches a boil reduce heat to medium and continue to cook about 15 – 20 minutes longer until potatoes are very soft.
Meanwhile, in a medium saucepan melt butter, add flour and cook for 1 minute while whisking.
Stir in milk then cook and stir until mixture begins lightly bubble and thicken.
Once potatoes are soft add thickened milk mixture to potato soup mixture and stir.
Add sour cream and mix well.
Top as desired.