Ingredients
For the sweet potato miso mash
800g/1lb 12oz sweet potatoes, peeled and chopped into large chunks
125g/4oz butter
1 tbsp roughly chopped rosemary
2 tbsp shiro miso (white miso)
salt
For the stew
2 tbsp extra virgin olive oil
2 large red onions, sliced
1 tbsp rosemary leaves
50g/2oz pine nuts
400g/14oz can chopped tomatoes, with liquid
2 tbsp soy sauce
1 kohlrabi, peeled, halved and cut into wedges
1 large head of cavolo nero, to yield 150g/5oz leaves, roughly chopped
1 tbsp shiro miso (white miso)

Method
1. For the sweet potato miso mash, start by boiling the sweet potatoes in lightly salted water until tender. Once cooked thoroughly, drain and set aside.
2. While boiling the sweet potatoes, heat a wide pan and add the oil, onions, rosemary and pine nuts. Sauté over a moderate heat, stirring frequently, to caramelise the onions, ensuring the nuts don't burn.
3. Add the tomatoes, soy sauce and 700ml/1 pint 5fl oz water to the pan. Bring to the boil, cover and simmer for ten minutes.
4. Add the kohlrabi and cavolo nero and mix in well. Cover and cook at a very gentle boil until the kohlrabi is just cooked, about 12-15 minutes.
5. Mix in the miso. Taste and adjust the seasoning, if necessary.
6. To finish the sweet potato miso mash, place the butter and rosemary in a small pan and cook over moderate heat until the butter turns a light nut-brown colour. Mash the potatoes with the butter and heat through, using the miso to season. Taste and add extra if needed.
7. To serve, divide the mash among four bowls and ladle the stew on top.