Step 1: Cook the Spaghetti: Bring a large pot of salted water to a boil. Add the spaghetti and cook according to package directions until al dente. Drain the spaghetti and rinse under cold water to stop the cooking process and prevent sticking. Set aside to cool completely.
Step 2: Prepare the Vegetables: While the spaghetti is cooking, prepare the vegetables. Dice the bell peppers, thinly slice the red onion, halve the cherry tomatoes, and halve the Kalamata olives. If using, dice the salami or pepperoni.
Step 3: Make the Vinaigrette: In a small bowl, whisk together the olive oil, red wine vinegar, Dijon mustard, minced garlic, dried oregano, salt, and pepper until well combined. Taste and adjust seasonings as needed.
Step 4: Combine Ingredients: In a large bowl, combine the cooled spaghetti, diced bell peppers, sliced red onion, halved cherry tomatoes, halved Kalamata olives, and diced salami or pepperoni (if using). Pour the vinaigrette over the mixture.
Step 5: Toss and Chill: Gently toss all the ingredients together until well coated with the vinaigrette. Add the grated Parmesan cheese, if using. Cover the bowl and refrigerate for at least 30 minutes to allow the flavors to meld together. This step enhances the overall taste and allows the salad to fully develop its vibrant flavors.
Step 6: Garnish and Serve: Before serving, give the salad another gentle toss. Garnish with fresh basil leaves, chopped. Serve chilled and enjoy!
Optional tips: Substitute different vegetables based on preferences, such as cucumber, carrots, or sun-dried tomatoes. For a creamier dressing, add a tablespoon of mayonnaise or sour cream to the vinaigrette. Vary the cheese; try feta, mozzarella pearls, or provolone. If preparing in advance, keep the dressing separate and add it just before serving to prevent the pasta from becoming soggy.