Prepare the bell peppers by cutting off the tops and removing the seeds and membranes. Mince the pepper tops, discarding the stems.

In a large bowl, combine the ground beef, minced pepper tops, onion, garlic, Italian seasoning, salt, and black pepper. Mix gently to distribute the seasonings.

Add the tomato paste, diced tomatoes with green chilies, and cooked rice to the beef mixture. Stir until well combined, being careful not to overmix.

Stuff each bell pepper with the beef and rice mixture.

Place a trivet or rack in the Instant Pot and add 1 cup of water. Arrange the stuffed peppers on the rack.

Secure the lid of the Instant Pot and set the valve to sealing. Select the 'Manual' or 'Pressure Cook' setting and set the timer for 10 minutes on high pressure.

Once the cooking time has finished, perform a quick release of the pressure according to the manufacturer's instructions.

Carefully remove the stuffed peppers from the Instant Pot, garnish with minced parsley if desired, and serve.