1. Cut the oxtail into sections, add ginger and boil.
2. After removing the scum, cover the pot and simmer for 2 hours. I use a cast iron pot, if you use a regular soup pot or pressure cooker, you can moderately increase or decrease the time.
3. Cut the onions into strips and fry them in a pan on low heat until the surface is golden and even slightly charred. This step is a little trick to increase the flavor of the soup.
4. Cut the potatoes, carrots and the remaining onions, add them to the pot with garlic, add salt, cinnamon and pepper, cover and cook for 20 minutes on medium heat.
5. Finally, add the green onions and the fried onion strips.