Steps

1. Peel 3 potatoes and remove any sprouts.
   🕒 01:11
2. Wrap each peeled potato whole in plastic wrap. [This is the trick!] Heating them whole without cutting allows the microwave's heat to penetrate evenly from the inside, cooking them uniformly.
   🕒 02:08
3. Microwave the potatoes for 2 minutes per 100g, for a total of 6 minutes.
   🕒 02:24
4. While the heated potatoes are still hot, mash them with a rubber spatula or similar tool while still wrapped in plastic wrap. [This is the trick!] Mash coarsely for a chunky texture, or mash thoroughly for a creamy, smooth texture.
   🕒 02:55
5. Transfer the mashed potatoes to a bowl.
   🕒 03:37
6. While still hot, add [A] 1/4 tsp salt, [A] 1 tsp sugar, and [A] 2 tsp vinegar to the bowl and mix well. [This is the trick!] Seasoning while hot allows the flavors to penetrate the potatoes well. Adding vinegar tightens the flavor even with less mayonnaise, resulting in a refreshing taste.
   🕒 03:46
7. Cover the mixed potatoes with plastic wrap and let them cool to room temperature.
   🕒 04:49
8. Trim the ends of 1 cucumber and slice thinly from one end.
   🕒 04:57
9. Place the sliced cucumber in a plastic bag, sprinkle with [B] 1/4 tsp salt, lightly coat, and let sit for about 5 minutes until wilted.
   🕒 05:20
10. Gently knead the wilted cucumber through the plastic bag. [This is the trick!] If you knead too hard from the beginning, especially with tough-skinned varieties, it can fall apart easily. Kneading after it has wilted helps you knead it well.
    🕒 05:56
11. Dice 3 slices of ham.
    🕒 06:13
12. Add all the salt-seasoned cucumber, including its liquid, to the bowl of cooled potatoes. [This is the trick!] The liquid from the cucumber contains nutrients and saltiness. Adding this makes the potatoes moist and smooth.
    🕒 06:40
13. Add the diced ham to the bowl and mix everything together.
    🕒 07:16
14. Add 2 tbsp mayonnaise and mix everything together while tasting.
    🕒 07:49