i buy the fresh chicken from the market or parkn' shop, then my maid will steam it and then put them into the blender and blend, then after the chicken is cool, she will put the small amount of the cooked chicken into the ice cube tray, and then put into the freezer ( enough for 1 week). everytime when you cook the congee , you can get one or 2 piece from the ice cube tray, and put into the congee when it is ready. before, you should take it from the freezer and put it down to the refrigator for thawing.
it is the method i followed from the book of the western writer.
I bought the frozen chicken before but 2 weeks ago, I started to buy the fresh chicken leg from the wet market. You may ask the shopkeeper to remove the bone and the skin. My maid will sliced the meat but keep a small portion and minced it. The sliced portion will boil with the rice while the minced portion will be put into the congee later on.