Heat some lard in a saucepan and lightly brown the onions in it. Add a little water, dissolve the bouillon cube in it and cook the kale in it. Season with salt, pepper and mustard. Halfway through the cooking time, add the sausages and let them get hot.
Peel the potatoes and cook them in salted water. Then mash and mix with the kale.
Arrange on plates and place the sausages on top. Serve with mustard.