Prepare the sauce: mix brown sugar with lemon juice until the sugar dissolves.
Add the mustard, olive oil and mayonnaise, whisking all the time.
At the end, put the chopped dill, salt and pepper.
The sauce should have the consistency of heavy cream, if it is too thin, add a little mayonnaise (you can also mix the sauce with a blender)
This sauce can be stored in the refrigerator for about a week, the next day it will become even tastier.
Our potatoes are ready (boil in a uniform), cut into medium pieces (do not mince), closer to the large ones.
Mix the potatoes with the sauce.
Cut the fish into thin pieces.
Spread the potato salad on the dish and add the fish slices.