In a blender or food processor, puree the tomatoes. In a saucepan, heat 1 tablespoon of the oil. Add the pureed tomatoes and bring to a boil. Simmer over moderate heat, stirring, until the sauce starts to thicken, about 5 minutes. Add the capers and oregano and simmer until the sauce is reduced to 1 1/4 cups, 5 minutes. Season with salt; keep warm.
Meanwhile, in a small bowl, cover the bread with the milk. Let stand until the bread has absorbed the milk, about 5 minutes.
In a large bowl, combine the ground pork and beef. Add the milk-soaked bread, egg, olives, cheese, parsley and 1 teaspoon of salt. Mix well with your hands and shape the mixture into 1 1/2-inch meatballs.
In a large skillet, heat the remaining 1 tablespoon of oil. Add the meatballs and cook over moderately high heat until starting to brown, about 1 minute. Reduce the heat to moderate and cook until browned all over and cooked through, about 8 minutes. Drain the meatballs and transfer to a platter. Pour the hot tomato sauce on top and serve.