Add olive oil to the pot. When oil is hot add the 1 cup of chopped onion and sauté for about 3 minutes.

When the onion is tender, but not browned, add the canned tomatoes, the seasonings and the water. Close the lid, turn exhaust vent to “air proof”.

When the cooking time has elapsed turn the keep warm feature off. While the sauce is cooking make the meatballs.

In a food processor, chop the onion, pepper and garlic together until very fine; add to the meats. Add the eggs, the seasonings, the bread crumbs and the cheese.

Using your hands, gently incorporate all the ingredients together and then form into 48 1 ½ -inch meatballs; set aside.

Prepare 3 quart-sized wide-mouth jars by running them through the dishwasher or hand washing with soap and very hot water. Place the flat lids into simmering water until ready to use.

Exhaust the pressure cooker until no pressure remains and the lid can be safely opened.

Open the lid, stir the sauce.

Using a long handle cup or ladle, carefully dip 3 cups of sauce into each of the 3 prepared jars. Wipe the jar’s lip clean and set aside.

Using the “set pressure cooking time” button reset the cooker to 25 minutes and press start.

Use tongs to carefully drop the meatballs, one at a time, into the sauce.

Stir the sauce gently, lower the lid and set the exhaust valve to “air tight”.

When cooking time has elapsed turn the keep warm feature off and let stand for 5 minutes before moving the exhaust lever into the exhaust position.

Using a long handled spoon, very carefully put 8 meatballs into each of the 3 quart jars.

Use a ladle to fill the jars with additional sauce until only 1 inch headspace remains.

Use a thin rubber spatula or chop stick to release any air trapped between the sauce and the jar by slowly going around the entire jar, pressing the food firmly to dislodge any air bubbles. Use a damp cloth to completely wipe clean the jar edge. Set the lid onto the jar and screw on the outer ring until tight, then unscrew ¼ turn.

Place the jars into the cleaned pressure cooker. Use a clean dish towel to tuck around the jars to prevent them from touching each other or the sides of the cooker.

Pour 6 cups of water into the cooker and close the lid. Set the time to 90 minutes and press start. When the cooking time has elapsed, unplug the cooker and let pressure release naturally.

Carefully remove the jars from cooker; they will be very hot! Set them on a towel or cooling rack and let cool completely in a draft-free location for about 12 hours.

Store in the cabinet and use within 1 year.