Mix with your hands or with a spoon until it is all mixed together.
Gently shape the mixture into balls about 3/4 of an inch in diameter.
Make the Soup
Turn the Instant Pot on Saute. Add the olive oil to heat.
1 teaspoon olive oil
Add the chopped onion and saute for 2-3 minutes to soften.
1 onion
Turn the Instant Pot off. Deglaze it by adding the beef broth. Scrape the bottom of the inner pan to make sure no bits of browned onion are stuck to it. This will reduce the chances of getting a Burn error notice.
2 cups beef broth
Add the celery, carrots, potatoes, garlic, Worcester sauce, oregano, basil, salt, pepper and tomato paste to the Instant Pot. Stir well.
Use your hands to gently push the meatballs down into the broth. Don't stir with a spoon as that will likely cause the meatballs to break apart.
Put the lid on the Instant Pot, making sure the pressure valve is closed. Set it for Manual, high pressure, for 8 minutes. It will take about 10 minutes for the pressure cooker to reach pressure.
Once the cooking time is done let the pressure release naturally for 5 minutes. Then release the remaining pressure and serve the soup.
Notes
You could use frozen pre-cooked meatballs instead of making fresh meatballs. No change in cooking time would be necessary.
This recipe also is delicious with turkey, pork or chicken meatballs. It would also be good with meatless meatballs if you want to make it vegetarian.