French Onion Soup

2 onions thinly sliced
1/4 c. butter
2 T flour
2 (10.5 oz) cans beef broth
1 1/2 c. water
1/2 c. Parmesan cheese grated
1/2 c. Swiss cheese grated
sour cream
sliced french bread

In a pan, saute' the onions in the butter over medium heat until the onions are caramelized-approx 20 min. Add flour and mix well. Gradually add the broth and water. Boil for approximately 25-30 minutes. While the soup is boiling, toast the french bread slices. Place a piece of toasted bread in each bowl. Top bread with cheese and dollop of sour cream. Pour the soup over the bread and serve.