Boil the spaghetti in enough water to cover them (about ½ galón [2 liters]) until slightly softer than al dente, having added 1 tablespoon of salt to the boiling water (set aside remaining salt). Drain the water and set the spaghetti aside.
2. Cook the sauce
While the spaghetti is boiling, heat oil in a large skillet or pot over medium heat. Cut the salami into cubes. Cook and stir the salami until it browns. Lower heat to medium-low. Add onions, bell pepper, olives, garlic, and capers and cook and stir for a minute or until onions become translucent. Add tomatoes and oregano, simmer covered until the tomatoes are cooked through (3-5 mins). Stir in tomato sauce and vinegar (do not add vinegar if you'll use milk). Stir to mix.
3. Mix spaghetti and sauce
Add milk and the boiled spaghetti and mix well. Stir until the milk is mixed through, but do not let it boil or the milk will curdle. Season it with black pepper and salt to taste.
4. Serve
This dish is best served hot. Garnish with the cheese.
Video
Notes
Do not add vinegar if you are using milk. Both ingredients are optional, as there are no two homes where this dish is made the same. Both versions have their fans, I love both.