For the meatballs:
1 pound 80/20 ground beef
1 clove garlic, minced
1/2 cup shredded mozzarella cheese
1/4 cup grated Parmesan cheese
2 tablespoons fresh chopped parsley
1 large egg
1 teaspoon Kosher salt
1/2 teaspoon fresh ground black pepper
2 tablespoons olive oil
For the sauce:
1 medium yellow onion, chopped
2 cloves garlic, minced
1 can (28 ounces) crushed tomatoes
1 teaspoon dried oregano
Kosher salt and fresh ground black pepper
In a large mixing bowl, combine the ground beef, garlic, mozzarella cheese, Parmesan cheese, parsley, egg, salt and pepper. Mix well with your hands until fully incorporated.
Form 16 meatballs from the mixture.
Heat olive oil in a large skillet over medium heat.
Add the meatballs to the skillet and allow to cook until browned on all sides and cooked all the way through, about 10 minutes.
Remove from the skillet and allow to drain on paper towels.
Add the chopped onions to the meatball drippings in the skillet and cook until translucent, about 5 minutes.
Add garlic to the skillet, and sauté until fragrant, about 1 minute.
Add tomatoes and oregano to the skillet, and stir.
Taste and adjust seasoning with salt and pepper. Allow to simmer, uncovered, for 5 minutes.
Add the meatballs back to the skillet, pressing them down into the sauce.
Cover the skillet, and allow to simmer, covered, until the sauce has thickened and the meatballs are hot throughout, about 15 minutes.
Serve directly from the skillet.
Garnish with extra Parmesan cheese and/or fresh chopped parsley.