Prepare the fruit the night before you plan to make the jam.  

Cut the rhubarb and strawberries into pieces and place in a large bowl along with the lemon juice and sugar.  

Stir and leave overnight for the sugar to draw out the water from the rhubarb.

When ready to make the jam put the jars in a medium oven for 10-15 minutes to sterilise them.  Be careful taking them out of the oven they will be very hot.  Use kitchen tongs to handle them.

Place them on a wooden chopping board as they come out of the oven - a cold surface may make the hot jars crack.

Place the fruit mixture into the preserving pan.    

Add the grated ginger and heat to dissolve the sugar.

Boil for about 5 minutes until the sugar has dissolved then continue cooking, stirring occasionally until the fruit is soft and the sugar dissolved .

To test for setting point take a clean plate out of the fridge or freezer - place a small dollop of jam onto the plate and let it cool. Run your finger through the jam and if it wrinkles then setting point has been reached.

Test for setting point and when it is reached pour into sterilised jars and cover with jam pot covers.

Leave to cool. The jam will thicken as it cools.