Season lamb meat with salt and pepper and set aside.
Heat oil over medium-high heat in a large, thick-bottomed pot or Dutch oven. In batches, add the lamb to the pan and sauté, stirring frequently, until it is well-browned on all sides. Transfer the browned meat to a separate plate or bowl, and repeat the process with the remaining lamb.
When done browning the last of the meat, lower the heat to medium-low and add the rest of the meat back to the pot. Add onions, garlic, ginger, and thyme, and cook, stirring frequently, for 3-5 minutes until the vegetables are softened.
Stir in the tomato paste and continue cooking for about 2 minutes. Sprinkle curry, coriander, cumin, and bouillon powder into the pot, and stir to fully combine the flavors.
Pour in the beef broth and water, bring the mixture to a simmer, then reduce the heat to low and cover the pot. Allow it to cook for approximately 60-90 minutes or until the meat is tender and easily falls off the bones.
Add the potatoes and bouillon powder 15-20 minutes before you remove it from the stove. Continue cooking until the potatoes are tender, and if you want a really thick curry, let the potatoes cook even more.
You may adjust the thickness of the curry with water or stock—season with salt and pepper to taste.
Garnish lamb curry with fresh parsley leaves and serve with rice. Enjoy!