1. Cook the pasta according to package directions and add to the large bowl. Toss with olive oil. Cool to room temperature.
2. In a small bowl, whisk together pesto, balsamic vinegar, zest and juice from one lemon, salt, and pepper.
3. Add mozzarella, red pepper, and yellow pepper to the pasta.
4. Pour dressing over pasta and toss to combine.
5. Top with grated Parmesan and pine nuts. Season to taste and serve at room temperature. Pasta salad can be made up to 2 days ahead of time covered in the fridge.