Steam the onion. Add the spices and tomato paste and sauté briefly. Add the carrots, lemon juice, raisins, bay leaf and cinnamon stick. Pour in the vegetable stock and simmer until the carrots are just firm to the bite. Add spinach, peas and corn and simmer for another 5 minutes. Meanwhile fry the sweet potato cubes in oil until crispy.
Pour the soup into plates and serve garnished with sweet potato cubes.