Mushroom and Potato Soup from Carol Jensen

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Cook over moderate heat 15 minutes:
... 3/4 cups carrots, diced
... 1/4 cup celery, diced
... 2 cups mushrooms, sliced
... 4 cups water or stock
... 1 1/2 tsp salt
... 1/4 tsp pepper

Add:
... 2 cups cubed potatoes
Cook an additional 15 minutes

Roux:
... 3 Tbl butter
... 1/4 cup flour
... 2 cups hot milk
Cook butter and flour until lightly brown, slowly add milk, cook until thick.

Add:
... 1 clove minced garlic
Cook an additional 20 minutes

note from transcriber: When is the roux added to the vegetables?