Chop onions. Save tops of green onions for later.
Melt butter and combine with oil in heavy
skillet over medium heat.
Add flour, stir. Cook roux, stirring frequently to avoid burning,
until light brown.
Add onions, celery and parsley. Cook til onions are clear.
Add
crawfish, stir, season with garlic, salt and peppers.
Add enough water (or stock) to make a
rather thick soupy mixture.
Cover and simmer over low heat about 15 minutes.
Stir in
chopped green onion tops.
Serve over rice.