Add one inch of water to a pot, then add the rhubarb and ginger. Cover and cook over a medium heat until the rhubarb begins to break down. Keep an eye on the pot to ensure the rhubarb doesn't catch on and stir occasionally.
Once it looks like the consistency in the picture, turn down the heat and transfer to a container to cool. Once cool, cover and put into the fridge to use over the next few days.