1. Wash the kohlrabi under lukewarm running water. Cut off the tender inner leaves and keep them to one side. Peel the kohlrabi, remove any woody parts, cut into quarters and then into fairly thick sticks.
2. Bring the water to the boil with the lemon juice. Place the kohlrabi in a sieve and suspend it in the boiling water. Blanch the kohlrabi for 5 minutes, rinse in cold water and drain it thoroughly.
3. Melt the butter in a large saucepan and braise the kohlrabi, stirring frequently. Add salt to taste, the sugar and stock and simmer for 15-20 minutes. Chop the kohlrabi leaves and mix them into the herbs.
4. Stir the creme fraiche and herbs into the kohlrabi.
Serve with: hamburgers and boiled potatoes.