Play around with the ingredients for different flavors – use seasoned instead of plain breadcrumbs, use another kind of hard cheese (halve the salt if using pecorino) or replace the oregano with hot pepper flakes.
1pound mixed ground meat(for example pork, beef and veal or just beef)
1large egglightly beaten
1/2celery stalkfinely chopped
2 3/4cups tomato puree
Quarter the onion and, using a mini-chopper, finely chop the onion (do not liquefy).
Add half of the chopped onion into a large mixing bowl put the half-full chopper aside.
To the bowl add the bread crumbs, cheese, oregano, pepper and 1 teaspoon of the salt, mix with a fork until well combined.
Next, add the milk and when that is mixed-in well add the ground meat.
Lastly add the egg and mix using your hands in a kneading motion until it is distributed – set aside.
To the heated pressure cooker (using Saute’ mode) add the olive oil and onion. While that is sauteing snap the carrot and celery into small pieces to fit in the chopper, finely chop and add to the pressure cooker.
Add the tomato puree, salt and water and mix well (saute’ mode on).
Move the bowl with the meat mixture next to the pressure cooker and start making meatballs – if you’re not handy at making them the same size you can use a tablespoon to measure the quantity of meat for each meatball.
As you make each meatball, drop them into the sauce. To get them in an even layer drop them in clockwise, then fill the center and start again with the second layer until you run out of meatball mixture – there is no need for precision here.
Close and lock the lid of the pressure cooker. Set the valve to “seal” and pressure cook for 5 minutes at high pressure.
Cook for 5 minutes at high pressure.
When time is up, open the pressure cooker with the 10-Minute Natural release method – move the cooker off the burner and wait for the pressure to come down on its own (about 10 minutes).When cooking time is up count 10 minutes of natural open time. Then, release the rest of the pressure slowly using the valve.
See serving suggestions above for making spaghetti and meatballs.