1 large apple 1 ginger root (say around 80 grams) 500 grams rhubarb 1 cup water 1200 grams sugar
Peel and cut the apple and ginger into small strips. Peel and cut the rhubarb stalks into one centimetre lengths. Put the fruits and water into a large pot and simmer slowly until soft. Add sugar and boil strongly until the setting point is reached. Rhubarb does not have a lot of pectin so you could add some before the cooking process if you wanted to.
Pour into warm sterilised jars and seal immediately.
The acid in the rhubarb plus the "heat" of the ginger means that this jam has a real punch. This suggests an alternative: cut the rhubarb finer, add a bit more water and do not necessarily cook it all the way to the setting point. The result will be a wonderful sweet sauce for ice-cream or similar deserts.