Melt butter in a large saucepan over medium heat. Add onion, celery, and garlic, and cook 3 minutes or until tender. Add curry powder and turmeric, and cook 1 minute. Add flour, and cook 2 minutes. Add broth, salt, and pepper, and simmer 10 minutes or until mixture begins to thicken. Add turkey and cream, and simmer 3 minutes or until heated through. Stir in lemon juice. Garnish, if desired.
*Be sure to look for curry powder that's imported or labeled "premium" for the best blend of spices.