Fill and boil your kettle. Tip the dried porcini mushrooms into a heatproof jug. Pour over enough boiling water to cover them. Peel and finely chop the onion. Trim and finely chop the carrot and celery to match the onion. Warm a medium pan on a medium heat for 1 min then add 1 tbsp olive oil and the chopped veg with a pinch of salt. Fry for 8 mins, stirring once or twice, till softened but not coloured.

While the veg cooks, peel and grate or crush the garlic. Finely chop the rosemary leaves. Drain and rinse the chickpeas. Fill and boil the kettle again. Drain the porcini mushrooms, pop them back in the jug and pour over 600ml hot water from the kettle.

When the veg has cooked for 8 mins, add the garlic and rosemary to the pan. Stir for 1 min. Pour in the chopped tomatoes, the porcini and their soaking liquid. Tip in the chickpeas. Pop a lid on the pan and simmer for 15 mins.

While the soup is simmering, finely shred the cavolo nero, discarding any thick or dry stems.

When the soup has simmered for 15 mins, stir in the cavolo nero and simmer for 5 mins till softened. Taste the soup and add more salt or pepper if needed. Serve in warm bowls.