In a large mixing bowl, mix all the ingredients together (ground turkey breast, salt, pepper, red pepper flakes, onion, garlic, parsley, an egg, milk, breadcrumbs, and parmesan cheese), and using your hands, mix it well until all the ingredients are evenly distributed.
Form the meatballs, about 2 tablespoons each.
Set Instant Pot to Sauté on high heat and add olive oil.
When the olive oil is hot, brown the meatballs in two batches, so they are in a single layer and don’t touch each other. Brown them for about 1-2 minutes each undisturbed on both sides, until they get brown color. Then remove from the pot.
Add chicken broth and scrape any burned bits from the bottom of the pot. Then add tomato sauce and mix. Bring it to the boil and let it simmer for about 5 minutes.
Transfer the meatballs back to the pot in a single layer.
Cover with a lid and cook on Manual high pressure for 5 minutes. Make sure that the venting knob is turned to “Sealing”!
When it is done, let it naturally release the pressure for 5-7 minutes. Then switch the knob to venting position and release the steam. Make sure the steam is fully released and the valve is completely down before opening the pot!
Serve with pasta, rice, or other grains of your choice.