Clean the skin of the potatoes, cook them as jacket potatoes and then peel them. Cut the streaky bacon and onion into small cubes and sweat in a pan with a little margarine until the onion cubes are translucent.
Make a roux from the margarine and flour in a saucepan and deglaze with the buttermilk to create a creamy bechamel sauce. Add the diced bacon and onion to the sauce and simmer gently for about 5 minutes. Then season the sauce vigorously with salt and Maggi.
Now cut the potatoes into cubes or slices and add them to the bechamel sauce. Let the bechamel potatoes steep a little and, if necessary, add salt and Maggi to taste. This goes well with meat loaf with fried egg.