Preheat the oven to 425 degrees F. Spray a baking sheet with cooking spray.
Whisk together the mustard and egg whites in a shallow pie plate. Combine the panko, Parmesan, lemon zest and parsley on a sheet of wax paper. Sprinkle the chicken with 1/2 teaspoon of the salt and 1/4 teaspoon of the pepper. Dip the chicken, 1 piece at a time, into the egg white mixture, then into the panko mixture, pressing to adhere. Place the chicken on the baking sheet. Lightly spray with cooking spray. Bake until the crust is golden and the chicken is cooked through, about 25 minutes. Do not turn.
Meanwhile, toss together the lemon juice, oil, arugula and remaining salt and pepper in a large bowl. Evenly divide the salad among 4 plates and top with the chicken.
Per Serving: 285 Cal; 34 g Protein; 6 g Tot Fat; 2 g Sat Fat; 3 g Mono Fat; 22 g Carb; 2 g Fiber; 3 g Sugar; 159 mg Calcium; 3 mg Iron; 814 mg Sodium; 69 mg Cholesterol