Combine yogurt and saffron in a bowl with pinch of salt. Line a sieve with cheese cloth and place sieve in something to catch liquid. Pour yogurt into cheese cloth and let strain at least 6 hours.
Clean lamb by removing excess fat and silver skin. Discard fat and keep silver skin for jus. Score the skin.
In a sauce pan on medium-high heat, brown lamb skin until deep brown. Add sliced shallots and garlic; cook until just starting to brown. Deglaze with red wine and reduce until almost gone. Add veal stock and reduce until thick. Turn off the heat and add the thyme. Season with salt and red wine vinegar if needed, depending on the acidity of the wine. Allow to cool slightly, strain and cool.
In a large pot, cover potatoes with water, then add bay leaves and salt. Cook until a knife slides easily into the flesh. Strain and allow to cool.
To assemble: Remove lamb from refrigerator; set at room temp for 1 hour. Season lamb heavily with salt and pepper.
In a heavy bottomed pan on medium heat, fry the skin side of the lamb. Add garlic and thyme to the fat that will render from the skin. Flip rump, place herbs on top and roast for 20 minutes on 350⁰F/180⁰C, or until internal temp of 150⁰F/64⁰C.
Reheat potatoes with peas in boiling water; toss with butter, salt and mint. Place on the bottom of the plate.
Carve lamb and garnish with labna and hot jus.