Combine Teriyaki sauce ingredients in a pot and heat to melt the sugar.
Set oven to 150°C. On an oven tray, line chicken thigh skin-down, then pour the chicken cooking liquid over the top until it covers half the chicken.
Cook for approximately 10 minutes, then turn over and cook for a further 4 to 5 minutes (check the largest piece to see if it is cooked through. If not, cook for longer.).
Once the chicken is cooked through, chargrill or BBQ until the skin is crispy.