Bring a large pot of salted water to a boil. Cook the spaghetti according to the package directions until al dente. Drain and rinse under cold water until completely cooled. Drain well.

While the pasta cooks, chop the tomatoes, cucumber, bell pepper, and red onion. Add them to a large mixing bowl along with the black olives and Parmesan.

In a small bowl or jar, whisk together the olive oil, red wine vinegar, lemon juice, Italian seasoning, garlic powder, sugar, salt, and black pepper until well combined.

Add the cooled spaghetti to the bowl with the vegetables. Pour the dressing over the top and toss gently until the pasta and vegetables are evenly coated.

Cover and refrigerate for at least 1 hour before serving. Give the salad another good toss just before serving. If it seems a little dry after chilling, add a small splash of olive oil and vinegar.