Bring a large pot of salted water to a rolling boil. Add the tri-color rotini pasta and cook according to package instructions, typically around 8-10 minutes, until al dente. Drain and rinse under cold water until cool.

In a large mixing bowl, combine cherry tomatoes, sliced pepperoni, chopped red onion, and diced green bell pepper. Stir gently to mix.

Incorporate mozzarella cheese and sliced olives into the mixture, folding carefully to maintain the pasta's integrity.

In a separate bowl, whisk together olive oil, red wine vinegar, Italian seasoning, garlic powder, salt, and pepper until well-emulsified.

Pour the vinaigrette over the pasta salad and toss gently until well coated.

Cover with plastic wrap and refrigerate for at least 1 hour before serving.

Stir gently before serving and present in a beautiful bowl, showcasing the vibrant colors.