Remove the excess fat from the roast if necessary, then cut the meat into 2-1/2" to 3" cubes and sprinkle generously with salt and pepper.
Melt a tablespoon of the fat in a large heavy skillet set over high heat. Add the chunks of meat in a single layer, making sure that the pieces do not touch, and cook until brown on all sides. Work in several batches if you have to and add more fat as needed. Remove the cooked pieces of meat to a 7 quart Dutch oven
Once all the meat has been browned, lower the heat to medium, add a little more fat to the pan if necessary, then throw in the onion, ginger, garlic and cherry pepper and cook, stirring often, until the onion is softened, fragrant and starts to turn translucent, about 5 minutes. Add the spices, stir to coat and cook for about 1 minute to develop the flavors, then add a cup and a half of water and continue cooking for another minute until the water is practically evaporated; add this to the meat in the Dutch oven.
In a bowl or measuring cup, whisk together the plain yogurt and remaining cup of water and pour that also into the Dutch oven, followed by the chopped cilantro. Stir well, cover and cook in the oven for 1-1/2 hours. After that time, stir well, remove the lid and continue cooking for another 30 minutes, until the meat is fork tender and the sauce has thickened.
Garnish with a handful of chopped cilantro and serve over a bed of white rice, with a little bit more yogurt, if desired.