Cut the chicken breast into bite-sized pieces.
Julienne the onion and carrot.
Heat olive oil in a pan and stir-fry the chicken breast.
When the chicken breast is cooked, add the vegetables and stir-fry together.
Season with soy sauce, mirin, and pepper.
Place the stir-fried chicken breast and vegetables over rice.
Garnish with green onion and sesame seeds.