In a deep skillet, melt 1/2 cup of unsalted butter over medium-low heat. Gradually whisk in 1/2 cup of all-purpose flour, stirring constantly for about 30 minutes until a rich, dark caramel color is achieved.

Once the roux reaches the desired color, add 1 chopped small yellow onion, 1 chopped medium green bell pepper, and the finely sliced stalks of 2 celery. Cook for about 5-7 minutes until the vegetables soften.

Stir in 1 pound of sliced Andouille sausage and 4 cloves of finely chopped garlic. Add 2 tablespoons of Cajun seasoning, kosher salt, and freshly ground black pepper to taste. Mix thoroughly for about 5 minutes.

Pour in 4 cups of low-sodium chicken broth, along with a 15-ounce can of fire-roasted diced tomatoes and a bay leaf. Stir well to combine and let it come to a boil.

Once boiling, reduce the heat to low and let your gumbo simmer gently for about 1 hour, stirring occasionally.

In the last 6 minutes of cooking, add 1 pound of peeled and deveined medium shrimp to the gumbo. Cook until the shrimp turn pink and firm, stirring carefully.

Finally, remove the bay leaf and serve your warm gumbo over cooked white rice, garnished with sliced scallions.