*Drain chickpeas and cover with cold water. Do not season. Bring water to boil and simmer, skimming off froth, until they are soft, about 1 hour. About 10 minutes before end of cooking, season with sea salt and freshly ground black pepper. Put chickpeas aside in their liquid.
Toast and grind the cumin and coriander seeds.
Heat olive oil in a deep saucepan on a high heat. Season and brown lamb pieces then remove and put to one side. Reduce heat and add garlic, onion and 1 tsp salt. Cook for 8 minutes then add ground spices, mustard seeds and paprika and cook until fragrant, about 2 minutes. Return meat to pan, add carrot, stir, then cover with stock. Bring to boil and simmer for 30 minutes, skimming any fat regularly.
Drain chickpeas and add to soup with the potato. Simmer for another 10 minutes, until potato is just cooked.
Check seasoning, ladle soup into soup bowls, garnish with freshly chopped herbs and serve with lemon wedges.
*If using tinned chickpeas, simply drain and add to the simmering soup to warm through before serving.