Cut the chicken breast and mushrooms into bite-sized pieces.
Slice the onion thinly.
Heat cooking oil in a pan and stir-fry the chicken breast.
Once the chicken is cooked, add the onion and mushrooms and stir-fry together.
Season with soy sauce, yuzu marmalade, and mirin.
Place the stir-fried chicken and mushrooms over rice and add a little more yuzu marmalade on top.