Andouille, a spiced, heavily smoked sausage, is the signature ingredient in this quick and easy classic Creole dish.
Remove lid from a 6-quart Instant Pot®. Press [Sauté], and use [Adjust] to select "More" mode. When the word "Hot" appears, swirl in oil. Add sausage; cook 4 minutes or until browned, stirring frequently. Remove sausage from cooker. Add chicken to drippings in cooker; cook 2 minutes on each side or until lightly browned.
Stir in 2 1/2 cups water and next 8 ingredients (through bay leaves). Close and lock the lid of the Instant Pot®. Turn the steam release handle to "Sealing" position. Press [Manual]; select "High Pressure," and use [-] or [+] to choose 18 minutes pressure cooking time. When time is up, turn cooker off. Open the cooker using Quick Pressure Release (page 4).
Stir in sausage, Old Bay seasoning, shrimp, and tomatoes. With lid off, press [Sauté], and use [Adjust] to select "More" mode. When mixture comes to a boil, turn cooker off. Press [Sauté], and use [Adjust] to select "Normal" mode. Simmer 5 minutes or until shrimp are done, stirring frequently. Turn cooker off. Remove inner pot from cooker; let stand 15 minutes before serving. Divide jambalaya among 8 bowls. Garnish with sliced scallions, if desired.
Swap In A Snap! Use smoked ham or chorizo if you can't find andouille.