Korean adobo andong jjimdak (braised chicken)

For the exact measurement: Chicken 1 kg. Sweet Potato Glass Noodles (soak into water to softened) 1 tbsp cooking oil 8 cloves garlic and 1 tbsp ginger (minced) 1/2 big white onion 3 chunk potatoes 1 whole thinly sliced carrots 3 cups water 1/2 + 1/2 bell pepper onion leek cut into 1/8 and other separate for garnishsliced thinly soak in cold water For the sauce: 1/2 cup of soy sauce 1/2 cup of oyster sauce 2 tbsp of corn syrup 1 tbsp of brown sugar