Walt Disney World Boston Clam Chower

3/4    lb margarine 
1 1/2    cups onion, diced 
1 1/4    cups celery, diced 
1 3/4    cups flour 
1/2    gallon hot milk 
1    quart clams 
1    quart clam juice 
1 1/2    cups green pepper, diced 
1/4    teaspoon white pepper 
1/4    teaspoon thyme 
2    cups potatoes, steamed for 12 minutes,diced 

1.  Melt margarine in dutch oven, add onions, celery and saute until tender. 
2.  Add flour to make a roux and cook over low heat 10 minutes, stirring constantly to prevent scorching. 
3.  Gradually add hot milk, stirring constantly to maintain smoothness.
4.  Add clam juice and chopped clams and cook 20 minutes more. 
5.  Add green pepper, thyme and pepper. 
6.  When green peppers are tender, add potatoes cut into small chunks and cook 10 minutes more. 

Source:   http://www.Recipezaar.com