Soak the skewers in a bowl of water while you prepare everything else, to prevent them from burning. Tip the soy, mirin, sake and sugar into a small saucepan, and cook over a medium heat for about 15 mins until the sauce is glossy.

Remove the skewers from the water and thread each one with a piece of chicken, followed by a piece of spring onion. Repeat twice more so the skewer is well stacked. Fill all four skewers.

Heat a large frying pan over a medium heat – you want to cook the chicken fairly gently so it soaks up the sauce. Put the skewers in the pan, then brush with the sauce. Cook for 10 mins, turning regularly and brushing in all the sauce. Serve immediately.