Place potatoes, celery, onion, water in 2 qt kettle, cover and cook till vegetables are tender.

Heat butter in 1 qt pan.

Stir in flour, salt, mustard, pepper and lowfat milk.

Cook 4 to 5 min or possibly till thickened.

Stir several times to keep from becoming lumpy.

Add in sauce to vegetables.

Cook another 2 min.

For Variation: Add in a small can chopped clams at the last and have a good clam chowder.