Steps

1. Peel the potatoes and cut them in half lengthwise.
   🕒 01:00
2. Cut the potatoes into 1-2cm thick slices.
   🕒 01:05
3. Place the sliced potatoes in a pot.
   🕒 01:14
4. Add enough water to cover the potatoes, then add 1 heaping tsp of salt. 【This is the key!】 Salting the potatoes while boiling enhances their sweetness and prevents them from becoming watery.
   🕒 01:31
5. Bring the pot to a boil and cook the potatoes for about 6 minutes, or until tender.
   🕒 01:57
6. Once the potatoes are tender, drain them in a colander and let them cool slightly.
   🕒 02:26
7. Chill the cooled potatoes in the refrigerator.
   🕒 02:35
8. Cut the cucumber in half lengthwise, then slice diagonally thinly.
   🕒 02:44
9. Slice the onion thinly.
   🕒 02:48
10. In a bowl, combine 300ml of water, 2 tsp of salt, and a handful of ice. Soak the sliced cucumber and onion in this mixture for 10 minutes.
    🕒 03:07
11. Hard-boil the egg, peel it, and chop it roughly.
    🕒 03:56
12. Cut the ham into bite-sized julienne strips.
    🕒 04:07
13. Remove the pickled cucumber and onion from the water and firmly squeeze out the excess water by hand.
    🕒 04:41
14. Place the chilled potatoes in a bowl and mash them to your desired consistency using a spoon or spatula.
    🕒 05:10
15. Add the chopped hard-boiled egg to the mashed potatoes.
    🕒 05:51
16. Add 3 tbsp of mayonnaise, a pinch of salt, a little pepper, and 1/2 tsp of whole grain mustard (if using) to the bowl.
    🕒 06:00
17. Before adding the cucumber and onion, mix well to ensure the mayonnaise is evenly distributed throughout the potatoes. 【This is the key!】 Properly coating the potatoes with mayonnaise is crucial for achieving the right flavor.
    🕒 06:37
18. Add the ham, the squeezed cucumber, and onion, and mix everything together.
    🕒 06:49
19. Taste and adjust seasoning. If it lacks richness, add more mayonnaise. If it lacks saltiness, add more salt.
    🕒 07:09