Turn the Instant Pot to sauté function and add in 1 tablespoon extra virgin olive oil and let heat for ~1 minute. Once the oil has heated, add in ½ small yellow onion (minced), 1 large carrot (sliced), and 1 large stalk celery (diced) and sauté for 2-3 minutes, stirring occasionally.
Once the onions begin to soften, add in 2 teaspoons minced garlic, ½ teaspoon dried oregano, ½ teaspoon dried thyme leaves, ¼ teaspoon crushed red pepper flakes, and 1 tablespoon tomato paste and sauté for 30 seconds just to lightly toast. Hit cancel to turn the Instant Pot OFF.
Add 3 cups low-sodium vegetable broth to the inner pot and vigorously scrape up any browned bits on the bottom of the inner pot.
Add ½ teaspoon kosher salt, ½ teaspoon pepper, 1 dried or fresh bay leaf, and 28 ounce whole tomatoes or diced tomatoes.
Place the lid on the inner pot and be sure the vent knob is sealed. Set to cook on HIGH pressure for 10 minutes. To do this, hit manual or pressure cook and use the +/- buttons to adjust the time to read 10.
Once the cooking time has elapsed, let the pressure release naturally for 15 minutes before doing a quick release of any remaining pressure.
Remove the lid, discard the bay leaf, add in ½ tablespoon balsamic vinegar Using an immersion blender, blend the soup until smooth. Alternatively, transfer the soup to a blender and blend with the lid slightly ajar to allow steam to escape and then add back to the inner pot. If using a blender, you may need to do this in batches.
If using, add ½ cup heavy cream to the inner pot and stir to combine. Place the lid back on the inner pot and let sit for 2-3 minutes, just to warm the cream through. Serve as desired.
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Notes
Tomatoes: If you can find them, use San Marzano tomatoes. The flavor truly is much better than regular canned tomatoes.Fresh Tomatoes: Replace the 28 ounces of canned tomatoes with 3-½ cups of peeled and seeded tomatoes (~ 10-12 Roma tomatoes.) Be sure to remove the peels and seeds for the best texture.Cream: Omit the cream for a lighter soup OR for a dairy-free/vegan version.Storage: Leftover tomato soup can be stored in the refrigerator for 4-5 days. I don't recommend freezing unless you didn't add cream, as the cream can separate as the soup defrosts.