Steps
1. Wash, peel and chop the sweet potato tubers into small chunks.
2. Boil the potato chunks until soft.
3. Drain off the water and mash the potato tubers.
4. Press the mashed potato through a sieve to form a puree.
5. Place the puree in a saucepan and add the brown sugar.
6. Slowly heat the mixture (stirring continuously) until all the sugar has dissolved.
7. Add the lime juice and mix well.
8. Add the fresh ginger and mix well.
9. Boil the mixture until it is very hot, stirring all the time.
10. Transfer the hot mixture into sterilised jam jars.
11. Half close the lids of the jam jars and place in a saucepan of boiling water. The water in the saucepan should come half way up the side of the jam jar).
12. Place a lid on the saucepan and boil the contents for 30 minutes.
13. Carefully remove the jars from the boiling water and close the lids very tightly.
14. Invert the jam jars and make sure that the jam touches the inside surface of the lid. After 1 - 2 minutes return jam jars to upright position.
15. Wipe the outside of the jam jars with a clean cloth.
16. Allow the jars to cool before labelling with the name of the product and date of manufacture.

Source
Food and Agriculture Organization of the United Nations (1994), Utilizing root crops, RAPA Publication 1994/30, Regional Office for Asia & the Pacific Bangkok, Thailand