Boil the potatoes in hot water.
For the sauce, first dice the onion very finely and sauté in the butter.
When the onions start to smell fine, sprinkle with the flour and pour in the milk. Bring to a boil and remove from heat.
Finely chop the dill and stir in, as well as salt and some pepper. If you like, add some bouillon cube.
Stir creme fraiche into the sauce, which is no longer boiling.
Peel cooked potatoes, add to the sauce and serve quickly.