Plug in the Instant Pot; choose the SAUTÉ setting. Add olive oil to the pot; let it heat up for about 1 minute. Dump in the chopped carrots, onions, celery, salt and black pepper. Sauté them, stirring occasionally, for 5 minutes OR until the veggies have softened slightly (don't let them get brown, though!).

Add the remaining ingredients to the onion/celery and carrot mixture. Stir everything very well until the ingredients are fully combined. The veggies won't be completely covered by the broth, but as they cook, they will release some of their own juices (or water) into the soup.

Put the lid on the Instant Pot; lock it into place. Flip the pressure release toggle to SEALING. Hit the CANCEL button to reset the Instant Pot and cancel the Sauté function. Now select the MANUAL or PRESSURE COOK button. Program the cooking time for 5 minutes at HIGH pressure. This will begin to bring the Instant Pot to full internal pressure (needs to happen before the cooking timer begins). It typically takes about 15-20 minutes for the Instant Pot to reach full pressure, then the pressure gauge will pop up on the lid, and the pressure cooking begins.

When the 5-minute cooking time has ended, the machine should alert you with a beep. Let the pressure release NATURALLY (do NOTHING at all to the Instant Pot) for a total of 15 minutes. Once the pressure has released naturally for 15 minutes, flip the pressure release toggle to VENTING. This will allow any more steam still inside the pot to release automatically. When all the steam has been released, the pressure gauge will drop back down into the lid, indicating it is safe to open the lid. Open and remove the lid; give the soup a stir. Find and discard bay leaf, because it is not needed anymore.

Ladle the soup into serving bowls. If desired, garnish each portion with grated Parmesan cheese and chopped flat-leaf parsley (or sprigs of parsley leaves). Serve hot and enjoy!