Cook the spaghetti according to the package instructions until al dente. Drain and rinse under cold water to stop the cooking process and cool the pasta. Set aside.
Prepare the Vegetables:
While the pasta is cooling, chop the cherry tomatoes, cucumber, red bell pepper, and red onion. Slice the olives and set everything aside.
Make the Dressing:
In a small bowl, whisk together the olive oil, red wine vinegar, Dijon mustard, honey, garlic, salt, and pepper. Taste and adjust seasoning as needed.
Assemble the Salad:
In a large mixing bowl, combine the cooled spaghetti, tomatoes, cucumber, bell pepper, onion, olives, and sweet corn (if using). Pour the dressing over the salad and toss everything together until well coated.
Chill and Serve:
Cover the salad and refrigerate for at least 30 minutes to allow the flavors to meld together. Before serving, sprinkle with shredded mozzarella cheese (if desired) and fresh parsley for a pop of color.
Serving and Storage Tips:
