This is tasty enough with slow-fried golden onions, but even better with onion gravy.
2 large onions, peeled and sliced Butter 300g (10 oz) cavolo nero 8 good sausages 1 Tbsp extra virgin olive oil 2 cloves garlic, peeled and crushed 1 tiny dried bird’s eye chillies, crushed, or a few pinches of chilli flakes (optional) ¼ tsp fennel seeds ½ tsp chopped rosemary Potato Purée & Onion Gravy (Link in Recipe Notes)
1 Put onions in a medium frying pan (skillet) with 2 tablespoons of butter and cook gently for about 35-40 minutes, stirring often, until tender and nicely golden. Don’t hurry this or the onions will scorch and taste harsh.
2 Cook sausages in a medium frying pan (skillet) over a gentle heat in 1 tablespoon of butter until golden and cooked through.
3 Meanwhile, prepare the cavolo nero by stripping the leaves off the stalks (discard stalks). Chop roughly. Plunge cavolo nero into a large saucepan of salted water and cook for about 5 minutes (until it softens but still retains some bounce), pushing it under the water from time to time. Drain and refresh with cold water until it feels cool. Shake dry then lay out on paper towels.
4 When onions and sausages are cooked, finish cavolo nero. Put oil in a medium saucepan with the garlic, crushed chilli or chilli flakes, fennel seed and rosemary and set pan over a medium heat. Cook briefly until fragrant and garlic is just changing colour, then add cavolo nero. Cook, stirring, until piping hot. Reheat onion gravy. Dish potato mash on to hot plates, top with sausages and onion gravy and serve cavolo nero on the side. Serve immediately.
If preferred, simply serve the golden crispy onions on top of the sausages instead of making the onion gravy – they’ll add a lovely sweetness to the meal.