The secret here is all about layering the flavors. You don't just want cold, plain chicken; you want meat that carries the soul of the dish.

1. Prep the Protein: Start by searing your chicken breasts in a hot pan with a tiny bit of oil. Let them develop a beautiful golden-brown crust. You should hear a steady, aggressive sizzle when they hit the pan. Once cooked, let them rest for at least five minutes. Cubing them while they are still slightly warm is key.
2. The Infusion: Place your cubed chicken in a bowl while it's still warm. Toss it immediately with two tablespoons of your pesto. The heat helps the oil and herb particles soak into the fibers of the chicken, rather than just sitting on the surface.
3. The Dressing: In a separate small bowl, whisk the remaining pesto with the lemon juice and olive oil. You are aiming for a consistency that coats the leaves without drowning them.
4. The Toss: In a large mixing bowl, combine the arugula, cherry tomatoes, and sliced red onion. Pour the dressing over the greens and toss gently. Add the warm, pesto-coated chicken last, so it doesn't wilt the greens too quickly.
5. The Finish: Top with the toasted pine nuts and a scattering of shaved parmesan. The crunch of the nuts against the tender chicken is pure magic.

If you’re prepping this for work lunches, keep the components modular. Store the washed and dried greens in an airtight container with a paper towel tucked inside to absorb excess moisture—this keeps them crisp for up to four days. Store the pesto-tossed chicken in a separate container. When you're ready to eat, combine everything and hit it with the lemon-oil dressing at the last possible second. If you dress the salad too early, the acidity of the lemon juice will break down the delicate cell walls of the arugula, resulting in a soggy, unappealing lunch.