Turn instant pot on sauté mode normal
Add oil and let it get hot
Add onion and cook for 3 to 4 minutes stirring occasionally
Add garlic and cook for additional 1 to 2 minutes
Add diced tomatoes and vegetable stock
Turn off sauté mode
Use Immersion blender and blend everything in the pot until smooth
Add potatoes, carrots, frozen vegetables, salt, pepper, cayenne pepper and sugar to the pot (if not using Italian seasoned tomatoes add oregano and basil)
Put lid on instant pot making sure the vent is closed
Pressure cook on high for 5 minutes with a natural release of 10 minutes
Release the rest of the pressure and remove lid
Stir and serve