Start by boiling the orzo in a pot of salted water, stirring occasionally. Cook until it feels al dente, about 8-10 minutes, checking the package instructions for exact timing. This step is crucial to getting that perfect texture in your salad; do not overcook!
Once the orzo's cooked, drain it and rinse it with cold water to stop the cooking process. This ensures the pasta remains al dente and prevents it from getting mushy. It should be cool to the touch afterward.
In a large bowl, mix the cooled orzo with basil pesto. Add the pesto a bit at a time, tasting as you go, to ensure balance and avoid making the dish overly oily.
Mix in the arugula, tomatoes, mozzarella pearls, and red onion. This will create a beautiful array of colors and textures, adding a fresh crunch to the salad. If the flavors of the onion seem too strong, you can thinly slice it to reduce its pungency.
Top your salad with balsamic glaze for a sweet tang, adding it just before serving to keep the salad from getting soggy. Use a light drizzle to avoid overpowering the other flavors.
Finish by adding the toasted pine nuts on top for a lovely crunch and nutty flavor. Ensure they are golden and fragrant; if they smell burnt, you should discard them and toast a new batch.