Peel and core the cucumber, cut into small pieces and put in the chopper.
Then cook in a saucepan over the highest heat for about 3 minutes. Turn through the brisk Lotte and pour back into the pot. Add the preserving sugar, lemon juice and citric acid and stir well.
Put the tarragon in a linen bag and cook with it. Cook over the highest heat for approx. 4 minutes.
Take a gel sample, then pour it into a twist-off glass.