Mix the sake, mirin, soy sauce, sugar, ginger and sesame oil in a dish that you can steep the chicken in: I use a 23cm square dish, but anything similar would do.
Add the prepared chicken pieces and leave for 15 minutes.>
Heat the groundnut oil in a large, shallow frying pan or casserole (that has a lid) and, using a slotted spoon, transfer the chicken pieces from their dark marinating liquid to the pan, and saute until they look cooked on the outside.
Pour the marinade over the chicken pieces in the pan and bring to a bubble, then turn down the heat to a gentle simmer, put the lid on and cook for about five minutes - cut into a piece of chicken to make sure it's cooked through.
Remove the cooked pieces with a slotted spoon (you could keep them warm in a bowl covered in foil) and turn the heat up under the pan to let the liquid boil down to a thick, dark syrup.
Return the chicken pieces to the pan, stir well so that they are all coated in the sticky, savoury syrup, then serve with a comforting pile of sushi rice and perhaps some steamed pak choi or greens of your choice.
Recipe from Nigella: Kitchen by Nigella Lawson (published by Chatto & Windus).