2. Raw materials: a pig bone (about 800- 1000g), cut into small pieces, half a fresh yam (also known as yam), one corn and one carrot, peeled and cut into large pieces, one ginger, and a little salt and pepper.
3. Wash the pig bones, put them in a large pot of cold water for five minutes, and then rinse them carefully with cold water.
4. Put pork bones and ginger into a pressure cooker, add eight bowls of cold water to boil, and then turn to low heat to let the water boil. Be sure to put enough water at a time, without adding water in the middle.
5. Add corn and carrots after one hour, continue to cook for one hour, add yam for another hour, put salt and turn off the fire. Simmer for a long time, the bones will be crisp and the meat will be rotten, and the soup will be more delicious.