Instructions

1. Place the lamb in a large bowl and cover with warm water. Let sit for 30 minutes, then pick the pieces out of the water and transfer to another large bowl or Tupperware. Mix the lamb pieces with the yogurt and turmeric, then cover with plastic wrap (or a lid) and marinate for 24 hours.
2. Blend the roughly chopped half-onion, ginger, garlic and tomatoes with 1 cup of water until smooth. Set aside.
3. In a 6- or 8-quart heavy-bottomed pot with a tight-fitting lid, heat the canola oil on medium heat. Once it starts to shimmer, add the remaining 2-1/2 onions and the sugar. Saute, stirring often, until the onions have softened and started to caramelize — this will take 20-25 minutes.
4. Stir in the turmeric, cayenne, coriander and cumin. Cook the spices for 5 minutes, until they’ve darkened and are fragrant.
5. Transfer the meat pieces to the pot (don’t dump the bowl in — you don’t want the meat juices that have collected at the bottom of the bowl). Stir until the meat is coated in the spices and onions, then add a teaspoon of salt. Cover and reduce the heat to medium-low. Cook, stirring occasionally, for 30 minutes, then stir in the ginger-garlic paste.
6. Cover and cook, stirring every 15 minutes, making sure to really pick up anything on the bottom (to prevent sticking/burning), for 60-75 minutes, or until the meat is almost tender. You should see the oil from the meat rising to the top, and the water from the meat should have cooked off.
7. Uncover the curry and stir in 4 cups of water. Simmer, stirring occasionally. After 15 minutes, add the potatoes. Continue to simmer until the potatoes and meat are tender (this took me another 30 minutes). Add salt to taste. Serve immediately, with rice, parathas or naan.