Wash the lemons hot, grate them dry and grate the peel thinly. Peel and chop garlic. Cut the meat rind crosswise. Season meat with salt and pepper. Rub the meat side with lemon and garlic. Roll up roast and tie with kitchen string. Cook in the preheated oven (electric cooker: 150 °C/ convection oven: 125 °C/ gas: see manufacturer) for approx. 4 hours
In the meantime peel, wash and roughly chop the potatoes. Cook in boiling salted water for about 20 minutes. Clean, wash and cut the leek into pieces. Bring cream to the boil, season to taste with salt and Sambal Oelek. Add leek to the cream, bring to the boil and braise for about 10 minutes
Bring milk to the boil and melt butter in it. Drain the potatoes. Add butter mixture and mash. Season to taste with salt and nutmeg. Remove meat from the oven and wrap in aluminium foil. Switch on the oven grill (240 °C) and grill the meat rind for 2-5 minutes. Arrange puree, leek and meat