Put sugar, tomatoes, ginger and chili into large pot and stand for 2,5 hours. Sugar will draw a lot of moisture out of tomatoes, you will now have a watery mixture.

Add the lemon juice and salt to your watery mixture and put the pot on low heat and stir until the sugar dissolves.

Turn the heat up and bring the jam to a rolling boil. It will get all frothy and bubbly. Stir constantly and boil like this for about 20 minutes. Then lower the heat and simmer for a further 15 minutes until it reduces and thickens, don't forget to stir.