Heat the vegetable oil in a large pan over medium heat. Add the cumin seeds, mustard seeds, fenugreek seeds, fennel seeds, and nigella seeds. Sauté for a minute until they start to sizzle and become fragrant.

Add the chopped onions and sauté until they become translucent and slightly golden.

Stir in the minced garlic and ginger, and cook for another 2 minutes until the raw smell disappears.

Add the turmeric powder, red chili powder, and coriander powder. Stir well to combine the spices with the onion mixture.

Add the chopped tomatoes and cook until they soften and the oil begins to separate from the mixture.

Now, add the bite-sized pieces of lamb to the pan. Cook and stir for about 5 minutes until the lamb starts to brown.

Lower the heat and add the plain yogurt. Stir it into the lamb mixture and cook for another 2-3 minutes until the yogurt is well incorporated.

Pour in enough water to cover the lamb, season with salt, and bring to a gentle simmer.

Cover the pan and let the lamb cook on low heat for about 45 minutes to 1 hour, or until it becomes tender and the oil starts to float on the surface. Stir occasionally and add more water if needed to prevent sticking.

Once the lamb is tender and the curry has thickened, remove it from heat.

Garnish with fresh coriander leaves and serve hot with lemon wedges.