Prepare some skewers and soak them in clean water for 30 minutes.
Meanwhile, beat the chicken breasts to an even thickness of 1cm. Cut into 3cm squares.
Cut the leeks into 4cm segments and the pepper into 3cm squares, and trim the stems on the mushrooms.
Prepare the skewers, alternately threading on the meat squares and the vegetables.
In a small billycan, combine the sugar, water, soy sauce and mirin and heat to dissolve the sugar. While it’s heating, crush and add the garlic, and stir in the pepper. Once the sugar has dissolved, set the glaze aside.
Begin cooking the skewers. It is traditional to have some skewers simply seasoned with salt, as well as those brushed with the sweet glaze.
Once the cooking has reached what you consider to be the halfway point, glaze the skewers that will be sweet. Do not worry if the glaze seems thin, it is built up in layers. Season the remaining skewers with a pinch of salt.
Continue glazing the sweet skewers little by little until they are cooked, and the glaze is a beautiful glossy brown. Cook the salted skewers until they too are golden. Serve hot.