Select sauté on your Instant Pot Pressure Cooker. Once it says “HOT,” add your italian sausage to the pot and cook until brown, breaking up the meat in the process.
Add the onion, celery, carrot, zucchini, and garlic cloves and stir until vegetables soften a little, about 3 minutes.
Press “Cancel” to turn of the Instant Pot. Add the chicken broth, lentils, dried basil, and oregano to the pot and stir.
Pour diced tomatoes on top of the mixture. Cover Instant Pot and Pressure Cook on High Pressure for 15 minutes.
When timer is up, allow to natural release for 10 minutes, then release remaining pressure.
Add fresh parsley and stir. Salt and pepper to taste.
Top with sour cream or parmesan cheese.