Prepare the peppers by cutting off the tops and removing the seeds from the inside.
In a large bowl combine raw ground beef, tomato sauce, 3/4 cup of tomato sauce, tomato paste, worcestershire sauce, diced onion, minced garlic, Italian seasoning, and salt. Mix until combined.
Add cooked rice and gently mix into the ground beef until well combined.
Stuff each pepper with ¼ of the ground beef mixture. It’s ok if it is slightly overfilled as the mixture will shrink as it cooks.
Pour 1 cup of water into your Instant Pot pot.
Place a trivet in the bottom of the pot and set your stuffed peppers on the trivet. Place a piece of foil over the pepper. This doesn’t have to wrap them completely I just like to cover the top of the pepper to keep water condensation from getting into the meat as it cooks.
Lock lid in place and turn valve to SEALING.
Set to HIGH pressure for 9 minutes.
When the timer goes off do a 10 minute natural release. After 10 minutes carefully turn valve to VENTING and release the remaining pressure.
When the pin drops remove the lid. Take the foil off of the peppers and use an instant read thermometer to check the the internal temperature of the peppers has reached 165 degrees F.
Top each pepper with 1 tablespoon of the remaining tomato sauce and 1 ounce of cheese on top of each pepper.
Place the lid back on the pot and let sit for 5 minute or until cheese is melted. If you like your cheese to brown a bit you can remove the peppers from the pot and place in an oven safe dish. Bake until the oven broiler set to HI for 5-7 minutes or until cheese is melted and lightly browned.