In a large bowl, use your hands to mix the ground beef, sour cream, egg, Parmesan cheese, kosher salt, and black pepper. Wet your hands and shape the mixture into 12 meatballs, each weighing about 2oz.
In a large, wide pot, heat the olive oil over medium heat. Add the garlic and cook, stirring, about 1 minute, just until golden. Add the tomato sauce, kosher salt, black pepper, onion powder, oregano and cayenne and bring to a boil.
Add the meatballs, spooning the sauce on top. Cover, reduce the heat to medium-low, and simmer the meatballs until they are cooked through, for about 30 minutes. Start checking on them after 20 minutes – they might cook faster, depending on your stove.
Remove the lid and turn the cooked meatballs in the sauce to coat. Garnish them with parsley and serve.
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Notes
For tender and fluffy meatballs, handle the beef mixture lightly. Try not to overwork it, or the meatballs will turn out dense.The sauce is mildly spicy. Depending on your personal preferences in terms of heat, you might consider using just ⅛ teaspoon of cayenne pepper. You can also omit the cayenne completely.