Season the rice with salt and pepper in a saucepan or pot. Cook the rice with the recommended water according to the instructions on the package. Once done, remove from heat and set aside. (Drain any excess water if needed).
Toss the chicken with cajun, salt, and pepper.
Heat a nonstick pan over medium heat. Once hot, add half of the oil and all the chicken, brown on all sides for 3 - 5 minutes, stirring occasionally. Then remove to a bowl.
Add the remaining oil, bell peppers, celery, onion, garlic, and thyme to the pan. Sauté until the vegetables start to turn translucent, stirring occasionally. Then add in the tomatoes and saute until they start to soften. Stir in the flour and cook while stirring for 3 - 5 minutes until the flour starts to turn golden brown.
Add the chicken broth, lemon zest, and chicken. Stir to combine. Simmer, stirring occasionally, until the broth becomes nice and thick and reduces concentrating the flavor. Season with salt to taste as needed. Adjust the lemon zest if needed, should just be complementary, don't overpower with lemon.
Mix with rice and garnish with scallions. Serve right away with bread.