Yam Tonic
1.
Complete medicinal materials
2.
Soak all medicinal materials in water for 30 minutes, rinse and set aside
3.
Put 2200ML of boiling water in the pot and boil all the ingredients (it is best to use a sand pot with other boiling water to add some)
4.
Boil on medium heat for about 90 minutes, then add rock sugar and cook for 5 minutes.