Prepare the chicken marinade by combining soy sauce, sugar, garlic, bay leaves and peppercorns in a bowl. Mix the ingredients until the sugar is dissolved.
Put the chicken in the marinade and mix with the chicken until well coated and let stand for 30 minutes.
In a pan or wok, put the chicken with the marinade and bring to a boil. Then simmer until the chicken is tender. Add some water if needed just in case the sauce is drying up.
Prick the chicken with a fork to check if the chicken is already cooked. Juices should run clear.
Taste the sauce and adjust the sugar and soy sauce if needed. Add in the spring onions and simmer for a few minutes.
Remove the chicken from the sauce and grill the chicken. Thicken the sauce by adding cornstarch and simmer until the sauce is thick. Arrange the chicken in a platter and pour some sauce and garnish with sesame seeds. Serve hot.