Preheat your oven to 200°C/Fan 180°C/Gas 6. Scrub your sweet potato and chop them into small chunks. Peel and thickly slice the onion. Place the sweet potato and onion into a roasting tray. Drop on the unpeeled garlic cloves. Drizzle over 1 tbsp oil and sprinkle over some salt and pepper. Slide into the hot oven to roast for 20 mins.

While the sweet potato is roasting, peel and finely grate the ginger.

When the sweet potato has roasted for 20 mins, remove the tray from the oven. Pluck out the garlic cloves and set them to one side. Dust over the ground coriander and stir through the grated ginger. Slide back into the oven to finish cooking for a further 15 mins.

When the sweet potato has 5 mins left to cook, fill and boil the kettle. Remove the tray from the oven when the potato has roasted for a total of 35 mins. It should be soft and lightly caramelised at the edges.

Place the tray on a medium heat on the hob (alternatively transfer the roasted veg into a large pan). Pour in 800ml hot water from the kettle. Squeeze in the roasted garlic flesh, discarding the papery skins. Bring up to a gentle simmer for 5 mins.

When the soup has simmered for 5 mins, add half of the sesame seeds. Using a stick blender, blend the soup till smooth, or transfer your soup, in batches into a blender. Taste the soup and add more salt or pepper if you think it needs it. Ladle the soup into warmed bowls and top with the remaining sesame seeds and a generous pile of the sprouts.