Sauté the onion in a pan with fat until translucent. Add the bacon cubes. Add the kale and add a little water to keep the kale from burning. Add sugar, mustard, salt, pepper and nutmeg to taste. Simmer on a low flame for at least 30 minutes, or even longer, if necessary, always add a little water.
Tip:
Can also be prepared a day in advance. The longer the kale can steep, the better the kale gets.
I always use branded kale, as I`ve had the experience that it turns out to be significantly better than others.