Wash leg of lamb, dab dry and rub with salt and pepper. Place on the fat pan of the oven and cook in the preheated oven (electric: 200 °C/ gas: level 3) for approx. 2 hours.
Gradually pour on about 1/2 litre of water. Wash the lemon, cut into slices and place in the fat pan 20 minutes before the end of the cooking time. In the meantime, peel the carrots (leaving a little green) and wash them.
Peel, wash, quarter and cut the kohlrabi into slices. Wash and halve the pointed cabbage and cut into wide strips. Cook kohlrabi and carrots in a little salted water for 12-15 minutes. Mix honey and mustard and brush the leg with it 10 minutes before the end of the cooking time.
Cook the pointed cabbage in a little salt water for about 5 minutes. Remove the leg. Pour stock through a sieve into a pot, fill up to 1/2 litre with water and bring to the boil. Add cream, stir in sauce thickener and bring to the boil.
Season to taste with salt and pepper. Melt the fat. Drain vegetables and arrange on a plate with the leg of lamb. Pour the fat over the vegetables. Sprinkle kohlrabi with chervil leaves. Garnish leg of lamb with lemon wedges and parsley.
Add extra sauce. Roast potatoes taste good with it.