Saute onion and garlic in ghee until translucent. Add curry powder and garam masala, and stir constantly until fragrant. Add water, lamb, carrots, and tomato, and bring to the boil. Reduce heat, cover, and simmer until lamb is quite tender. Remove lamb from stock, and chop finely, discarding bones. Add back to simmering soup along with the lentils. Simmer for about 10-15 min., stirring often, until lentils are tender. Add stock cube, salt and pepper to taste, and broccoli. Simmer until broccoli is tender but still bright green. Serve with lemon wedges for squeezing.