In the insert the Instant Pot, add the olive oil, carrots, and onion. Using the sauté mode cook, stirring often, until the onions are translucent, 2-3 minutes.

Add the tomatoes, broth, basil, sugar, salt, oregano, and baking soda. Stir together and be sure to scape the bottom of the insert to remove and bits on the pan.

Put the lid on the Instant pot and be sure the valve is set to seal. Cook on high pressure for 10 minutes. Allow the pressure to naturally release for 10 minutes before quick releasing the remaining pressure (if liquid spurts through the valve, close the valve, wait a few minutes and try again).

Carefully use an immersion blender (or transfer the soup in batches to a blender) to puree the soup until smooth. Return the soup to the pot if using a blender.

In a bowl, whisk the milk, half and half, and flour until very smooth. Add to the soup while whisking.

Turn the sauté mode and cook, stirring constantly, until the soup is heated through and thickened. Season to taste with additional salt and pepper, if needed (this is important to do). Serve immediately.