Place 1 diced medium green bell pepper, 1 diced medium yellow onion, and 3 diced celery stalks in a medium bowl.

Place 6 minced garlic cloves, ½ cup coarsely chopped fresh parsley leaves (if using), 2 tablespoons of the salt-free Cajun seasoning, 2 teaspoons dried thyme, 2 bay leaves, and ½ teaspoon cayenne pepper in a small bowl; stir to combine.

Season 1 pound diced boneless, skinless chicken thighs with 1 ½ teaspoons kosher salt, 1 ½ teaspoons black pepper, and the remaining 1 tablespoon Cajun seasoning.

Cook 14 ounces sliced andouille sausage in a large pot or Dutch oven over medium-high heat until the sausage is browned all over and releases its fat, about 5 minutes. Transfer the sausage to a plate.

Add 1 tablespoon of the neutral cooking oil and the chicken to the pot. Cook, stirring often, until the chicken is browned all over, about 10 minutes. Using a slotted spoon, transfer the chicken to the plate of sausage.

Reduce the heat to medium. Scrape up any browned bits from the bottom of the pot with a wooden spoon. Add 4 tablespoons unsalted butter, the remaining ¼ cup neutral oil, and ½ cup all-purpose flour. Cook, stirring constantly and scraping the bottom of the pot with the wooden spoon, until the roux resembles the color and texture of melted milk chocolate, 10 to 20 minutes. It will go from smelling like flour to toasted popcorn to nutty coffee. Don’t turn your back on the roux or it will burn!

Increase the heat to medium-high and add bell pepper mixture. Stir to coat in the roux. Cook, stirring frequently, until the onions are translucent, about 10 minutes. Add the garlic mixture and return the sausage and chicken and any accumulated juices to the pot. Cook, stirring frequently, until the garlic is fragrant, 2 to 3 minutes.

Add 6 cups low-sodium chicken broth. Increase the heat to high and bring to a boil. Reduce the heat to medium-low and simmer uncovered until the gumbo is thickened slightly and the flavors have melded, 35 to 45 minutes. Meanwhile, cook white rice for serving if desired.

Taste and season with more kosher salt as needed. The gumbo can be served immediately or the day after (which is when it tastes best). Serve with a scoop of cooked white rice, thinly sliced scallions, a dash of Crystal hot sauce, and filé powder as desired. Filé powder adds herbal notes and thickens the gumbo a bit.