Marinate the lamb shanks in the Street Kitchen Rogan Josh garlic and ginger paste and set aside.
Heat the mustard oil in an oven-proof dish over high heat, allow to heat for 3-4 minutes before starting to cook. Add the Street Kitchen spice mix to the hot oil and leave for 5 seconds, then immediately add the lamb shanks and saute for 5-7 minutes until browned off and sealed.
Add the Rogan Josh sauce, red onions and 1/2 cup stock and bring back to a simmer. Cover with a lid and place into oven for 3-3 1/2 hours or until meat falls off the bone. Remove from the oven and place shanks onto serving platter along with whole onions, stir through the yoghurt into the sauce and pour over the shanks.