In a large soup pot, cook the diced potatoes in the chicken stock until tender. Strain the potatoes from the stock, and reserve both potatoes and stock.
Melt the butter in the pot, add the onions and celery, and cook until the onions are translucent. Add the flour and cook, stirring constantly, until the flour turns golden. Add the reserved chicken stock, a little at a time, whisking until smooth. Stir in