Trim and prepare the turnip tops (or purple sprouting or Tenderstem broccoli and leafy greens) by stripping off the leaves and finely slicing any tough stalks.
Crumble the sausage into pieces.
Put a tablespoon of pork fat or olive oil in a frying pan on a medium-high heat, saute the sausage, stirring, for a minute, then stir in the butter beans with their liquid.
Add the greens, the lemon zest and juice, and an optional pinch of chilli flakes, to taste.
Cover the pan, bring to a boil, then turn down the heat to low and simmer slowly for 10 minutes, until the greens are very soft – stir occasionally, and add water, if need be, to stop the beans catching. Season to taste and serve topped with grated cheese of your choice (pecorino, parmesan or mature cheddar, say) and an optional drizzle of extra-virgin olive oil.
