swiss chicken wings

so in hong kong we often ate swiss chicken wings.  not sure how it got its name but its basically soy sauce chicken.  i didnt have wings so i used whole thighs. also not sure why the recipe calls for blanching the chicken?  maybe to keep the skin on?  i felt like it might have made the chicken a bit more dry ...

Ingredient:
6 frozen chicken wings in whole, around 700-750g
1 thick slice ginger
3 stalks spring onion

Sauce:
5 tbsp light soya sauce
5 tbsp dark soya sauce
1 tbsp sesame oil
1 tbsp Shaoshing wine (or any Chinese wine)
2 pcs rock sugar ( table tennis), break in small pieces
2 cups of water

Method:
1 unfreeze the chicken wings, wash and rinse
2 blanch the wings in boiling water for 1 min, remove and put in cold water, raise
3 heat 2 tbsp oil, fry the ginger slice and spring onion for around 1 min, add thesauce and boil until all sugar dissolve
4 add the wings in the sauce until reboil
5 turn to light fire, cover then keep boil around 15 mins
6 turn the wings to another side, off the fire, leave the wings in the sauce with cover for another 10 mins.