Turn your Instant Pot to the "saute" function and saute your onion in the oil for a couple minutes until tender.
Add in the rice and continue sautéing for an additional 2-3 minutes, stirring constantly.
Add in the chicken broth, diced tomatoes (with juices), and seasonings to the rice. Stir til combined.
Put lid on the Instant Pot and ensure that the valve is set to "sealing".
Press the "pressure cook" button and set to three (3) minutes cook time.
When cook time is complete, allow Instant Pot to naturally release for about 10 minutes, then do a manual release until the pin drops.
Remove lid and fluff rice with a fork before serving. ENJOY!