Chicken Katsu: Butterfly your chicken breasts and flatten each breast to ~1cm thick
Prepare your drenching station. Coat chicken breasts into flour then eggs and lastly in the panko breadcrumbs. (Take your time to make sure every part of the breast is coated well)
Heat up your pot of oil to 175C/350F and deep fry the cutlets one at time for around 2-3 mins on each side. Remove from oil and rest on paper towel or on wire rack.
Tonkatsu sauce: In a pan over low-med heat, melt your butter and add in the flour to form a roux. Continuously whisking to remove lumps and cook out the floury taste for 1-2 mins.
Slowly add into the worcestershire sauce, ketchup, water and sugar into your roux mixture and whisk until thick. Feel free to add in more water to adjust consistency of sauce.
Salad: Combine mayo, ketchup, lemon juice and sugar in a bowl. Place over cabbage as dressing.