Peel the sweet potatoes and cut them into equal pieces. Heat some olive oil in a soup pan and sauté the sweet potatoes over high heat. Chop the onion and garlic, and add them to the pan.
Cut the tomatoes into 4 wedges and remove the stem end. Sauté the tomato wedges for a minute. Add just under a litre of vegetable stock and bring close to boiling. Cook the potatoes until done. Check whether they’re done with a fork.
Use a hand blender to puree the soup in the pan or blend it in several times with a heat-resistant kitchen blender. Taste the soup and season with harissa seasoning, salt and pepper. Taste again. Harissa is a spicy and often hot blend. Keep the soup warm on the stove, but avoid boiling it.
Clean the pomegranate. Cut the skin into four segments, but do not cut all the way through. Break the pomegranate into segments to easily remove the seeds.
Serve the soup into the plates, garnishing with pomegranate seeds, coriander, cashew nuts, grated lime zest and some wafer-thin garlic slices, if desired. Finally, make flavour drops of oil, harissa and lime juice.