Wash leg of lamb and pat dry. Rub with salt and pepper. Place on a grid over the fat pan. Roast in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 2 hours.
In the meantime, clean and wash the soup greens and cut them into large pieces. Put the soup greens and rosemary on the fat pan for the last hour. Pour 1/8 litre of broth over each leg at intervals of about 15 minutes.
In the meantime, peel and wash the potatoes and carrots. Cook in boiling salted water for about 15 minutes. Clean and wash the zucchini. Cut lengthwise into thin slices. Cook in boiling salted water for about 5 minutes.
Shortly before serving, toss in hot fat. For the sauce, pour the roast stock through a sieve. Stir 3 tablespoons of cream and flour until smooth. Bring the rest of the cream and stock to the boil. Bind with the flour. Season to taste with salt, lemon pepper and juice.
Arrange the leg with vegetables and sauce. Serve garnished with fresh herbs and lemon.