Cajun Seasoning: Use storebought cajun seasoning, or, to make your own, in a small mixing bowl, whisk together all spices to make cajun seasoning. Set aside.
Cook Vegetables and Sausage: In a large pot over medium-high heat, heat avocado oil before adding bell peppers, onion, and celery and sauteeing until softened, about 5 minutes, stirring occasionally. Add in sliced sausage and cook for an additional 5 minutes, stirring occasionally.
Add-In And Simmer Remaining Ingredients: Stir in frozen cauliflower rice, diced tomatoes, chicken broth, and prepared cajun seasoning. Increase stovetop heat to medium-high, stir in shrimp and bring mixture to a simmer and cook until shrimp is pink and cooked throughout and liquid has slightly reduced, about 4-5 minutes.
Final Steps: Taste and add additional salt, pepper, and/or cayenne pepper, based on your taste preferences. Garnish with fresh parsley and serve.