Mix all ingredients in a large bowl by hand or using a wooden spoon. Shape mixture into even meatballs, about the size of a golf ball. Preheat oven to 350 F. Heat the oil in a large oven safe skillet. Fry the meatballs until evenly brown. Pour in the Marinara sauce and transfer the skillet into oven. Bake for 20 minutes. Serve immediately.