Bring a large pot of salted water to a roaring boil and cook the pasta to al dente according to package instructions.
Drain and rinse under cool running water until just warm to the touch.
Transfer to a large mixing bowl and toss with a ¼ cup of Italian dressing and a generous pinch of salt.
Set aside and allow to cool completely while you prepare basil and onions.
Add the tomatoes, mozzarella, olives, and basil to the bowl, along with the remaining ½ cup of Italian dressing.
Toss to combine and season to taste with salt and pepper.
Chill thoroughly. Optional: top with basil chiffonade.
Optionally, add sardines, or cold or warm chopped chicken.
