Mix oil and flour in a 4 quart measuring cup. Microwave uncovered on high 6-8 minutes. Stir at 6 minutes. Roux should be a light brown color. Cook 30-60 seconds longer to give dark brown color. Roux will be very hot handle cup carefully. Add onion, celery, and bell pepper to roux in cup. Stir and return to microwave. Cook on high 3 minutes.
Add garlic, parsley and green onion to roux; stir and return to microwave. Saute on high 2 minutes.
You will have about 3-3/4 cups roux. If there is oil risen to top spoon off. Slowly add hot water to roux to 4-cup mark. Stir. Roux freezes well, and you will be ready on a moment's notice to prepare a delicious gumbo or stew.
Cajun Country -- New Iberia, Louisiana