Put the meat in a large bowl and add the bread crumbs, Parmesan and sour cream and mix with your hands. Add the remaining ingredients, except the vegetable oil, and combine well. Roll into about 20 or so balls, about 2 inches in diameter.
Heat the vegetable oil in a large skillet over high heat. When the oil begins to smoke lightly, shut off the heat (to avoid splattering). Add the meatballs in a single layer and spread somewhat apart so they have a chance to "brown" instead of steaming. Put the skillet back on high heat and brown the meatballs, turning them so they brown all around. Treat them like hamburgers and cook them until they are medium-rare, about 3 to 5 minutes. Touch them to make sure they are still tender in the center.
Add the meatballs to the hot tomato sauce and allow them to bubble slightly and simmer over very low heat for a few minutes. Shut off the heat and allow the mixture to "rest" for a few additional minutes before serving.
Recipe courtesy of Alex Guarnaschelli