Heat convection oven to 350°F. In a stockpot, bring chicken stock to strong simmer and hold simmering.
Season chicken with salt and pepper. In a separate stockpot, heat oil over medium-high heat until shimmering. Add chicken; cook until browned on all sides, about 5 minutes. Remove chicken and set aside.
Add sausage; cook until just starting to brown, about 2 minutes. Remove sausage and set aside with chicken. Add vegetables and cook until lightly golden, about 6 minutes, scraping brown bits from pot.
Stir in tomato paste; cook until lightly browned, about 1 minute. Add RedHot Sauce and first amount (2 tbsp) of Vietnamese Cajun Seasoning; stir to combine. Return chicken and sausage to pot. Stir in rice until combined.
Transfer mixture to hotel pan. Add hot chicken stock. Stir well to combine. Cover tightly with foil. Bake in preheated oven 40 minutes. Remove from oven and fluff rice, folding in remaining Vietnamese Cajun Seasoning (3 tbsp). Serve hot.
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