Brown the Sausage: Set the Instant Pot on SAUTE function and set it on HIGH heat mode. Add oil and when the oil becomes moderately hot gently release the ground sausage and saute until nicely browned.
Saute Aromatics & Seasonings: Add the chopped onion and garlic and saute for 1-2 minutes. Than. add all the dry seasonings mentioned in the "Seasonings" section above in the ingredients section. Saute another 1-2 mins or until the onion begins to turn soft. CANCEL the SAUTE function.
De-Glaze Pot: Pour the chicken stock and de-glaze the pot really well by scraping the sides and the bottom of the pot with the help of a spatula to loosen any stuck food particles. This is very important and will prevent the BURN error.
Add Lasagna Sheets: Now, add the tomato paste, canned Italian style diced tomatoes & the Balsamic vinegar. Give everything a quick stir. Than, add the broken Lasagna Sheets into the pot. Gently push them towards the bottom of the pot as much as you can so that they are covered with the liquid. DO NOT stir or mix.
Pressure Cook: Now, pour the Marinara sauce all over the Lasagna sheets so that they get completely covered with the sauce. This is important. DO NOT stir. Secure the lid of the Instant Pot seal the valve and PRESSURE COOK on HIGH for 5 minutes. It'll take about 10-15 mins to build the pressure as it's a lot of soup.
Quick Pressure Release: Once, the pressure cooking cycle is over perform a quick pressure release (QPR) manually by moving the valve from the sealing to the venting position. Open the lid carefully. Note: If you want a thinner soup now is the time to add an extra cup of chicken stock, you can also add more according to your preference.
Stir & Serve: Stir the Lasagna Soup gently to mix everything in the pot. Dish out the soup and top it with Mozzarella and Ricotta Cheese. We love chopped fresh parsley as well. Dig in! Enjoy.