In a large bowl, combine ground beef, cooked rice, shredded cheese, egg, finely diced onion, minced garlic, salt, and pepper. Mix gently and form into meatballs.

Set your Instant Pot to the sauté function, heat oil, and add the onion and garlic. Cook until fragrant and translucent, about 2-3 minutes.

Pour tomato sauce over the sautéed vegetables and carefully place the meatballs into the sauce.

Set the Instant Pot to manual pressure cook for 10 minutes and allow a natural pressure release for 5 minutes.

Remove meatballs with a slotted spoon and serve with your favorite sides.