Jerusalem artichoke soup (sunchoke soup)

To make soup

1. Peel and cop the onion in a medium dice. Peel and finely chop the garlic, if using.
2. Prepare a bowl with cold water and set beside you while you prepare the Jerusalem artichokes. Peel the Jerusalem artichokes and cut them into medium-small chunks. As soon as you have peeled and chop one, place the pieces in the bowl of water then move onto the next piece.
3. Once all the vegetables are ready, warm the butter in a heavy-based pot/pan large enough to hold all of the vegetables and stock over a medium heat. Add the onion and cook for a couple minutes so that the onion softens and becomes tranlucent.
4. Add the garlic and Jerusalem artichokes and stir, ensuring they are well coated in the butter. Cover and leave to sweat/cook for around 3 - 4 minutes.
5. Add the stock, cover and bring to a simmer. Once simmering, reduce the heat and continue to simmer for around 20 minutes until the Jerusalem artichokes are tender. Meanwhile, make the pangrattato/crumb topping.
6. Meanwhile, make the pangrattato/crumb topping.

To make pangrattato/crumb topping

1. Remove the crusts and break up the bread into medium breadcrumbs (they don't need to be very fine). Finely chop the garlic and chop the parsley.
2. Warm the olive oil in a skillet over a medium heat and add the garlic. Cook briefly, for only around a minute, just to soften and bring out the fragrance but don't let it burn.
3. Add the breadcrumbs and toast for a few minutes until the crumbs are dry and lightly browned all over, stirring and turning regularly.
4. Remove the crumbs from the heat and mix through the parsley and lemon zest. Set aside while you finish the soup.

To finish and serve

1. Once the Jerusalem artichokes are soft, remove the soup from the heat and blend until smooth. You can either use an immersion/stick blender in the pot or transfer to a blender if needed. Adjust the seasoning with a little salt and pepper, as needed.
2. Serve the soup, topped with the pangrattato/crumb topping (only add right before eating and if you like, a little at a time).