Roasting (optional)

If you like a little extra flavors and bright color then roast the tomatoes, onions and garlic. Line them on a baking sheet, drizzle oil on it and roast for 40 minutes at 400 F or 200 C.

Don't throw away the juice from the tomatoes. 

Instant Pot Tomato Basil Soup (if roasted as above)

Turn on the Saute mode, heat some oil, throw in the Italian herbs, fresh or dried whatever is handy. 

Add in the roasted onions, garlic, tomatoes, fresh basil and liquid, salt .

Cover the lid, seal the vent and pressure cook for 6 minutes followed by a quick release of pressure.

Instant Pot Tomato Basil Soup (if you skipped roasting)

Using the saute function, add oil in the pot.

Add the onions and garlic and saute until the color changes.

Once the onions have changed color, add the tomatoes, fresh basil and liquid, salt and sugar.

Cover the lid, seal the vent and pressure cook for 10 minutes followed quickly releasing the pressure.

Blend

Use a hand blender or a stand blender, to blend the soup until you get a smooth consistency.

Garnish

With fresh basil leaves, red pepper flakes, crushed black pepper and some olive oil if you like.