500g rhubarb, peeled and cubed (make sure it's ripe)
1 tsp ground ginger
500g sugar
Put the sugar and ginger in with the fruit in a large thick bottomed pan and stand for 12hrs.
Stew the fruit SLOWLY until the sugar has dissoved stirring occasionally. You can tell the sugar has dissolved by tapping your wooden spoon on the bottom of the pan: if you don't hear any crunching noise, it's done!
Once the sugar has dissolved, boil the jam rapidly.
Test the jam is ready using a jam thermometer or by weighing the jam (having weighed your empty cooking pot before you start), you should get about 830-850g of jam.
When your jam is ready, take it off the heat. If it has a lot of scum on it, remove this or stir it in if it only has a little.
Put the jam in clean, warmed jars and place a wax paper circle on it straightaway, seal the jar and label as appropriate.
Store in a cool dark place.