Add oil celery and onions and heat until tender (5-6 mins).
Peal potatoes and dice into small pieces. Put potatoes in after onions and celery are ready. Take off heat and fill up pot half way with water. Add salt.
Boil until Potatoes are tender (~15 minutes).
In separate bowl, mix 4 Tab. of flour and slowly add 1/2 cup milk, stir with fork (NO LUMPS).
Take soup off heat before adding mixture and milk. Add cup of milk to soup then add mixture, put back on medium heat and continue to stir. If too thick add more milk.