Strain oyster liquor into saucepan. Remove any bits of shell from oysters. Melt margarine, stir in flour in liquor until smooth. Don't brown. Add white part of onions and celery. Cook until soft. Add milk, green onions and seasonings, and stir until smooth. Do not boil.
In meantime, cook oysters in liquor until oysters plump and edges begin to curl (about 4-5 minutes - don't overcook). Skim off top. Combine with milk. Sprinkle with minced parsley. Serve at once.
Four to Six servings.
Cajun Country -- New Iberia, Louisiana