Making the meatballs: In a bowl mix beef, egg, 1/2 teaspoon of pepper, onion, breadcrumbs, garlic, 1 tablespoon of salt and work the mixture together until thoroughly mixed. Roll the mixture into 16 equal-sized balls, flatten the balls and place a mozzarella cube in the center, shape again into balls making sure the mozzarella is completely covered.
Cooking the meatballs: Heat the oil in a large skillet over medium. Cook the meatballs, turning carefully as they cook until they have browned. Pour in the tomato sauce, covering the meatballs. Add the oregano. Cover and lower the heat to low while the pasta is cooked.
Cook the pasta: Follow packet instructions for al dente pasta, adding 1 tablespoon of salt to the water before adding the pasta to it. Once cooked-through, drain the pasta.
Mixing everything: Taste the tomato sauce and season with salt and pepper to taste. Mix the pasta and meatballs and tomato sauce. Remove from the heat.