Heat the oil in a large saucepan and fry the onion cubes until translucent. Add the kale and fry vigorously, then add the diced potatoes. Add the bacon strips and rind and fry for another 5 minutes. Add the sausages and mustard and deglaze with the stock. Reduce the heat and simmer for about 40 minutes. Season to taste with salt and pepper.
Tip:
If you reheat the stew the next day, it tastes at least twice as good!