Start instant pot on saute mode. Add oil and once hot stir in the onions and garlic. Saute until onions are translucent and the raw garlic smell disappears.
Stir in the salt, pepper, dry oregano, and red chili flakes. Then add the tomatoes, basil, and vegetable broth. Give it a good mix. Ensure nothing is sticking to the bottom.
Close the Instant pot lid with vent to sealing and cook on manual (pressure cook) high for 6 mins. Followed by natural release.
Open the lid and puree the soup (using a hand blender) until smooth. Or wait for it to cool and then transfer to a blender and blend.
Start the Instant pot again on saute mode to bring the soup to a boil.
Give it a taste and adjust salt and stir in some sugar to balance the tartness (if required).
Finish off with some freshly cracked black pepper.
Cozy and comforting soup is ready!!