Cook the potatoes:
Wash and chop the potatoes, then place them in a large pot. Cover with cold water, add a pinch of salt, and bring to a boil. Cook until potatoes are fork-tender. Drain and set aside to cool slightly.

Prepare the crab:
Open the package of imitation crab and gently separate the chunks. Lay them in a single layer on paper towels. Place another sheet of paper towel over the top and press gently to absorb excess moisture. Set aside.

Make the dressing:
In a large mixing bowl, combine the mayonnaise, champagne vinegar, salt, pepper, and fresh dill. Stir with a spatula until well mixed.

Assemble the salad:
Add the cooled potato chunks to the bowl with the chopped cucumber, diced hard-boiled eggs, and corn. Gently toss to coat with the mayonnaise mixture.

Add the crab:
Carefully mix in the crab, taking care not to break up the delicate pieces. Gently toss until evenly incorporated.

Chill and serve:
Transfer the salad to a food-safe container and refrigerate for at least 2 hours. This salad can be made in advance and will keep for 2-3 days in the fridge.