Dice the onion and set half aside for the sauce.
To the bowl add the bread crumbs, salt, pepper, and onions - mix with fingers.
Add the milk, mix again.
Add the ground meats.
Add the egg and knead together.
Roll up 30-35 meatballs.
Put InstantPot on sautee, add olive oil and remaining onion.
Add part of the water to deglaze after onion has carmelized. Add remaining water, crushed tomatos, and tomato paste.
Drop meatballs into the sauce.
Turn off saute function, put lid on pot, close the steam valve and set Manual HP for 5 minutes.
NPR for a minimum of 10 minutes.
Cook pasta separately.