Trim and dice the rhubarb. Place into a large pot and add the water. Cover with a lid and cook over moderate heat for 20-25 minutes until the rhubarb has completely softened.

Remove the pan from the heat and use a soup ladle to scoop out the hot liquid and pour into a jug. Add the sugar-free jelly powder to this hot water mixture and whisk well. Once dissolved, add it back into the rhubarb in the pan and add the lemon juice. Stir well to combine.

Use a potato masher to further break down the rhubarb, then pour the mixture into a clean bowl. Cover and place in the freezer for at least 6 hours.

Remove the mixture from the freezer and use a fork to ‘break up’ the mixture. Pour in the lime soda and use a whisk to mix in.

Combine between two cocktail glasses (or 4 smaller ones) and enjoy!