Select and clean the raspberries. Put them into a steam juicer, add lemon juice and bring to the boil. Juice raspberries, measure 900 ml juice. Let the juice cool down.
Bring raspberry juice, lemon grass, vanilla sugar and jam sugar to the boil and boil for 3 minutes while stirring until bubbly. Remove lemon grass. Fill jelly brimful into 4 clean twist-off glasses, close them and leave them on the lid for about 5 minutes. The jelly can be stored for 2 years