Add the rhubarb pieces to a large saucepan. Heat over a medium high heat and add in the water plus the lemon juice, cardamom pods and the ginger. Stir then bring to a simmer and cook for around 8-10 minutes, stirring occasionally.

Once the water has reduced down a bit and the rhubarb is softening turn down the heat low and bring to a gentle simmer. Add the lemon zest, salt, vanilla extract and the sugar. Stir through. Gently simmer for another ten minutes until the rhubarb has completely broken down into small strands. Taste the compot. Too sharp in flavour still? Then add another 2-3 tsp sugar and stir though. Adjust until you get the sweet/sour balance to your liking.