Whisk together mustard, lemon juice, mint leaves, and olive oil in a small bowl. Set aside.
In a large bowl combine red onion, feta, tomatoes, olives, cucumber, parsley, and quinoa. Add dressing and toss to coat. Refrigerate to allow flavors to marry for a minimum of 30 minutes before serving.
Preheat grill to medium high. Season chicken with Imperial Salt Free Signature seasoning blend. Grill until chicken has reached an internal temperature of 165°F. Allow to rest for 10 minutes and then slice.
Place 4 oz sliced chicken over top of 3/4 cup of quinoa salad.