Preparation

• Combine the breadcrumbs and milk in a mixing bowl and let sit for 5 minutes.
• Heat the oil in a heavy 12-inch skillet over medium heat. Add the onion and cook, stirring often, until translucent, about 5 minutes. Add the tomatoes and their juices, 1 cup water, and 1/2 tsp. salt and 1/4 tsp. pepper. Increase the heat to high and bring to a boil. Lower the heat to a steady simmer and cook for 15 minutes.
• While the sauce simmers, prepare the meatballs: Mash the breadcrumbs and milk with a fork to a smooth paste. Add the beef, pepper flakes, half of the parsley, 1-1/2 tsp. salt, several grinds of pepper to the breadcrumbs. Mix with your hands until thoroughly combined. Wet your hands to keep the mixture from sticking to them and roll into 1-1/2-inch balls; you should have about 30.
• Arrange the meatballs in the sauce, cover, and cook for 10 minutes. Remove the lid and continue to simmer for another 5 minutes to thicken the sauce. Stir in the remaining parsley and season the sauce with salt and pepper to taste.