Place the chopped Cajun trinity in the bottom of a cast iron skillet or Dutch oven.Top with cold butter.
Cook over medium high heat. After 5 minutes, stirring the melting butter or oil into the trinity.
Continue to cook down the veggies until browned, stirring often.
Make the tapioca, arrowroot, or corn starch starch slurry by whisking the starch with ⅓ cup of the water or broth. Get the salt ready. Set both aside.
When the trinity caramelizes at about the 24 to 28-minute mark, sprinkle the salt over the top. Wait about 45 seconds, then stir.
Add the other ⅓ cup of water or broth to the mixture. Let steam for 15 to 30 seconds, then stir.
Whisk the slurry into the mixture, and add the remaining cup of water or broth. Whisk for at least 2 minutes over the medium-high fire, or until all lumps are removed. Use another cup of broth or water, if you need to, to keep the roux wet enough to whisk all starchy lumps out, if necessary.
Use immediately in place of an oil and flour roux in a stew. Double the Trinity Roux™ for a gumbo or large soup.
