Boil potatoes with their skin on, then peel them. Hard boil the eggs, remove the shell. Dice the cucumber and onion.
For the dressing, put the vinegar, oil, spices, herbs, mustard and honey in a bowl, add the onions and beat the ingredients with a hand blender until creamy.
Cut the potatoes, hard-boiled eggs and cucumber into cubes and add to the dressing with the celery salad (including juice). Mix everything carefully and let the salad stand overnight.