Wash chicken legs, pat dry and season with salt. Place chicken legs on a baking tray and roast in a preheated oven (electric: 200 °C/ gas: level 3) for 35-40 minutes.
In the meantime, clean the carrots (leave some green as desired) and wash them. Clean, wash and slice the kohlrabi. Put the carrots in boiling salted water and cook for about 12 minutes.
Put the kohlrabi in boiling salted water as well and cook for about 10 minutes. In the meantime clean and wash spring onions and cut them into rings. Melt the fat in a pot. Dust with flour, sweat on and gradually deglaze with stock and cream while stirring.
Bring to the boil, season to taste with lemon juice, salt, pepper and sugar. Keep warm. Heat oil in a small pan and fry spring onions in it at medium heat for about 2 minutes. Season with salt and pepper.
Drain the vegetables. Arrange carrots, kohlrabi, chicken legs and spring onions on a plate. Spread some sauce over them and serve garnished with lemon and chervil as you like. Add the rest of the sauce garnished with lemon julienne.