Turn the Instant Pot to the “Sauté” function and heat the olive oil. Add the smoked sausage slices and cook for 4-5 minutes until browned. Remove the sausage and set it aside.
- In the same pot, add the diced chicken thighs and cook for 5-6 minutes, until browned. Remove and set aside with the sausage.
- Add the onion, bell pepper, celery, and garlic to the pot. Sauté for 3-4 minutes until softened and fragrant.
- Stir in the Cajun seasoning, thyme, paprika, oregano, cayenne pepper (if using), salt, and pepper. Cook for another 1 minute to allow the spices to bloom.
- Add the diced tomatoes (with juices), chicken broth, uncooked rice, and bay leaves. Stir well to combine.
- Return the cooked sausage and chicken to the pot. Close the lid, set the Instant Pot to “Manual” or “Pressure Cook” for 10 minutes on high pressure.
- When the cooking time is up, perform a quick release of the pressure.
- Open the lid and add the shrimp to the gumbo, stirring to combine. Close the lid again and let the residual heat cook the shrimp for 5-6 minutes, until pink and opaque.
- Discard the bay leaves. Taste the gumbo and adjust seasoning as needed. Serve the gumbo with a sprinkle of fresh parsley and a dash of hot sauce, if desired.