Cook sausage in a Dutch oven over medium-high heat, until cooked through. Transfer cooked sausage to a medium bowl.

Return the pan to medium-high heat and add oil. Add onion and cook, stirring often, until translucent, about 2 minutes.

Add bell pepper and celery, and cook till crisp-tender, 5 minutes.

Add garlic and Cajun seasoning and cook, stirring often, until fragrant, about 30 seconds.

Add flour and cook, stirring to coat the vegetables, until the flour browns, about 1 minute.

Stir in broth and roux, cover, increase heat to high and bring to a boil.

Return the sausage to the pan, along with okra and rice; reduce the heat to a simmer.

Cook until the okra is heated through and the rice is tender, about 20-25 minutes. Add shrimp or chicken in towards the end of this step, depending on how long shrimp needs to cook through or chicken needs to warm up.

Serve sprinkled with sliced scallions.