Emeril Lagasse says the word étouffée means "smothered," and in Cajun and Creole cooking refers to anything cooked in its own juices, sometimes with a bit of water or other liquids as well. The evaporation is kept to a minimum so that the flavors stay intense. His book Louisiana Real & Rustic includes the following recipe for Crawfish Étouffée
Melt 1/4 pound of butter (one stick) in a large skillet over medium-high heat. Add 2 cups of chopped onions, 1 cup of chopped celery, and 1/2 cup of chopped bell peppers and sauté for 10 to 12 minutes, until the onions are soft and golden. Add a pound of peeled crawfish tails and 2 bay leaves. Reduce the heat to medium, stir occasionally and cook "until the crawfish begin throwing off a little liquid" - another 10 to 12 minutes.
Meanwhile, dissolve a tablespoon of flour in a cup of water. Add it to the crawfish mixture and season with a teaspoon of salt and 1/4 teaspoon of cayenne pepper. Stir about four minutes until the mixture thickens. Add 2 tablespoons of chopped parsley and 3 tablespoons of chopped green onions and cook for another 2 minutes. As always, remove the bay leaves before serving.
We resisted the urge to kick this answer up a notch by inserting the word BAM! before the addition of each ingredient - and are pretty proud of our self-restraint.