Wash the meat, dab dry, season with salt, pepper, coriander and cinnamon, tie into shape with kitchen string. Wash thyme, shake dry. Peel onions and garlic, chop finely. Set aside 3 cloves of garlic.
Heat 2 tablespoons of oil in a frying pan. Brown the meat all around. Add onion, garlic and thyme, deglaze with broth. Braise open in the preheated oven (electric cooker: 150 °C/ circulating air: 125 °C/ gas: see manufacturer) for about 1 1/2 hours.
Peel and wash the potatoes, cut them into pieces and cook them in boiling salted water for about 15 minutes. Dice the beetroot finely, put something aside for garnishing. Puree the rest with crumbled feta, yoghurt, 1 clove of garlic and lemon juice, season to taste with salt and pepper.
For the Gremolata, finely chop 2 garlic cloves. Wash the herbs, dab dry. Remove leaves and chop finely. Mix garlic, herbs and citrus peel, season with salt.
Drain the potatoes and let them evaporate briefly. Add 4 tablespoons of oil, place the lid on top and shake vigorously (holding the lid firmly). Distribute on a tray, season with salt. Take the leg of lamb out of the oven and put it aside covered.
Bake the potatoes in a preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: see manufacturer) for approx. 20 minutes until golden brown. In the last 5 minutes of the baking time, turn the potatoes and spread butter in flakes on top.
Take the lamb out of the stock, cut it open. Pass the stock through a sieve and heat. Arrange meat with potatoes and beetroot dip on plates. Sprinkle dip with beetroot set aside, sprinkle Gremolata over the meat, garnish with orange slices.
Drizzle the stock over it or add it. Serve with a lamb's lettuce with nut vinaigrette.