In a small saucepan, mix sugar, soy sauce, vinegar, pepper, starch diluted in 50 ml. cold water, grated ginger and garlic.
While stirring, bring to a boil, the sauce should thicken. Grease a baking sheet with butter.
Put the chicken. Pour the sauce thoroughly and send it all to the preheated oven (220 degrees) for 30 minutes.
Stir every 5 minutes so that the chicken is well soaked in the sauce.