Chop the onion, celery, and bell pepper into small, even pieces to create a colorful flavor base.
Heat vegetable oil in your heavy-bottomed pot over medium heat until shimmering, then add the sliced sausage. Cook until browned and crispy around the edges, about 5 minutes, releasing a savory aroma.
Add the chicken pieces to the pot and cook, stirring often, until no longer pink and slightly golden, about 8 minutes. This builds a rich, meaty foundation for the dish.
Stir in the minced garlic, paprika, cayenne, and thyme, cooking for about 1 minute until fragrant and the mixture turns a deep, aromatic hue.
Pour in the crushed tomatoes and chicken stock, stirring to combine everything and bring the mixture to a gentle simmer. You should see bubbling around the edges.
Stir in the rinsed rice, making sure it’s evenly distributed in the liquid. Cover the pot and reduce the heat to low, allowing it to simmer gently for 20 to 25 minutes, until the rice is tender and has absorbed most of the liquid.
Periodically check the dish, adding a splash of hot chicken stock if it begins to dry out, ensuring the rice stays moist and flavorful.
Once the rice is tender and the flavors meld together, turn off the heat and let it rest, covered, for about 10 minutes. This helps the flavors settle and the dish develop a cohesive texture.
Fluff the jambalaya gently with a fork to aerate the rice, then taste and adjust the salt and spice levels as needed. Serve hot, garnished with fresh herbs if desired.