Make a roux with oil and flour (stir ingredients on medium heat until med/dark brown) in large pot.  Add onion, celery, green onion and  bell pepper and sauté until tender.  Add a little water if vegetables start sticking.  Add butter, seasoning, parsley, salt, pepper and beef broth.  Cook 30 minutes.  Add crawfish tails and cook 15 minutes.  Serve over cooked rice.