Remove the pomegranate seeds from the fruit and set them aside. Wash the sweet potatoes and cut them into cubes of about 4 cm. It’s perfectly fine if the cubes are not exactly equal in size, but you may want to try and keep them consistent. Dice the apple as well.
Dice the red onion and sauté them in olive oil along with freshly ground pepper. Add the salt only at the end when the stock is added to the soup.
Add the diced sweet potatoes to the pan and sauté for a few minutes, stirring regularly. Then add the apple cubes, 1.5 litres of water, and the vegetable stock. Let it simmer over medium-high heat for about half an hour until the sweet potatoes are completely softened.
Turn off the heat, add the Italian herbs and half of the pomegranate seeds. Puree until smooth, and taste to see if the flavour is to your liking. You may prefer a slightly fresher taste.
Serve the soup in bowls, garnish each bowl with the remaining pomegranate seeds, and add a sprig of mint if desired.