Wash chicken thighs under running water and cut into bite-sized pieces. Slice onion and mushrooms thinly.

Mix soy sauce, sugar, mirin, oyster sauce, and honey in a bowl to prepare the sauce. Set aside.

Beat the eggs lightly, leaving some texture. Set aside.

Heat a pan with a little oil and place chicken thighs skin-side down. Cook over medium heat.

Once the chicken is white on the surface, add sliced onions, placing them underneath the chicken. Cook until onions turn translucent.

Add enough water to cover the bottom of the pan and pour in the prepared sauce. Simmer over medium heat.

Add mushrooms (if using) once the sauce has reduced slightly. Continue simmering until the sauce thickens.

Pour the beaten eggs over the chicken and sauce. Stir gently and cook until eggs are semi-set.