1Heat the oil in a large pot. Add the onion and cook until translucent.
2Drain the soaked chickpeas and add them to the pot together with the vegetable stock. Bring to the boil, then reduce the heat and cover. Simmer for 30 minutes.
3In the meantime toast the cumin in a small ungreased frying pan, then grind them in a mortar. Add the garlic and salt and pound to a fine paste.
4Add the paste and the harissa to the soup and simmer until the chickpeas are tender, about 30 minutes.
5Season to taste with salt, pepper and lemon juice and serve hot.
