Using the saute function on your pressure cooker, sauté the onion in butter for 2 to 3 minutes, or until the onion is softened. Add the garlic and red pepper flakes and cook 30 seconds more.

Pour in the broth and scrape the bottom of the Instant Pot to release any browned bits. This is an important step to prevent the auto-shutoff due to a "burn" error. Plus, all that flavor is going into the soup!

Add the chopped carrots, crushed tomatoes, sugar tomato paste, and Italian Seasoning; stir.

Lock the lid in place and set the Instant Pot to HIGH pressure for 10 minutes. Once cooked, release the pressure naturally for 10 minutes followed by a quick release of any remaining pressure.

Use a handheld immersion blender to puree the tomato soup until smooth. You can also use a blender or food processor.

Taste and season with salt and pepper as needed. Add 1/3 cup of additional broth or milk to cream to thin the consistency if desired. Ladle into bowls and serve!