Mix salt, peppers, basil and thyme together. Set aside.
kosher salt, cayenne pepper, black pepper, white pepper, dried basil and dried thyme
Heat 7 tablespoons olive oil in a heavy pot until smoking ( 3 to 4 minutes). Gradually whisk in flour. Whisk until roux is about the color of peanut butter (3 to 4 minutes). You must whisk constantly and don't take your eye off the roux even for one minute. It starts browning quickly. If you burn the roux, dump it out and start over.
Remove from heat and add prepared onions, celery and bell pepper and one tablespoon of the dry seasoning mix. Keep stirring constantly until the roux has cooled, approximately 5 minutes.
Bring stock to boil in a large saucepan. Gradually whisk in roux. After it's well incorporated, reduce heat, continue stirring and cook for an additional two minutes. Set pot aside.
Heat 3 to 4 tablespoons olive oil in a large saucepan (at least 4 quart) over medium high heat. Add shrimp and green onions. Cook for 2 minutes, constantly stirring.
Add cooked crawfish meat.
cooked crawfish tail meat goes into the pot
Gently stir it in.
Add the gravy and three tablespoons of butter to the pan with the seafood and onions. Shake the pan until the butter metlts. Add remaining dry spice mixture, stir and remove from heat.
For each serving, make a ring of rice in a serving bowl, add etouffee in the center. Serve immediately.