In a casserole filled with salted boiling water, start cooking orzo. Add asparagus in the casserole 3 minutes before pastas finishes its cooking. Rince under cold water and drain.
In a pan, heat oil at medium heat. If desired, spread greek seasonings over chicken breasts. Cook chicken breast for 12 to 15 minutes, until chicken flesh isn't pink anymore, while turning over at mid-cooking. Then mince.
In a large bowl, mix orzo with asparagus, chicken, vinaigrette, onion and parsley.