I originally did this some years ago from a BBC recipe with real vanilla pods, but the recipe below is with frozen rhubarb (less than half the prize than fresh) and vanilla extract and it is just as good as the original one.
- 1 K of frozen rhubarb
- 1 K of jam sugar
- juice of 1.5 lemons
- 1.5 teaspoons vanilla extract
- and the essential ingredient for making jam without any stress: a jam thermometer (£8 in Lakeland - totally worth it)
Put the rhubarb, jam sugar, vanilla extract and the juice of a lemon in a big pan over medium heat. Let it simmer for a good 22-25 minutes until the rhubarb goes mushy. My children do not like big bits of fruit in the jam, so as soon as a rhubarb is soft I press it down a few times with a potato masher. Keep the heat on for another 10-14 minutes until the mixture reaches 105 degrees. Take the pan off the heat and add the juice of the half lemon. Let it rest for a few minutes and pour it into sterilised jars (just rinse the jars with water and microwave them for 2 minutes). You should get 5 jam pots from this.