Heat the olive oil in a medium saucepan over medium heat.
Add the chopped garlic, diced onion, celery, and bell pepper. Sauté until the vegetables soften, about 3-4 minutes.
Stir in the Cajun seasoning and diced tomatoes, letting the flavors meld for another minute.
Add the diced chicken breast and shrimp, cooking gently until the chicken is mostly cooked and the shrimp turn pink, about 5-6 minutes.
Pour in the chicken broth to create a light simmer, and let the gumbo cook for an additional 3 minutes to ensure all proteins are tender and infused with flavor.
Meanwhile, in a separate pan, lightly sauté the cauliflower rice until warmed through, about 2 minutes.
To serve, layer the cauliflower rice in a bowl, then spoon the gumbo mixture on top.
Finish with diced avocado sprinkled over the top for a creamy contrast, and enjoy your spicy, hearty meal.