Slice the onion thinly and separate the shimeji mushrooms by hand.

Cut the chicken thigh into small bite-sized pieces.

Heat salad oil in a frying pan over medium heat, add chicken, and sauté until the color changes. Add onion, shimeji mushrooms, and salt and pepper. Cook for about 3 minutes until the onion softens and the chicken is cooked through.

Add water to the pan and bring to a boil. Turn off the heat and add cream stew roux, stirring until dissolved. Then add milk and heat on low until the edges of the pan bubble gently.