Japanese Potato Salad - cooking recipe

Ingredients

3 medium boiling potatoes, such as yukon gold
1 small carrot (optional)
1 large egg (optional)
1 small onion
4 inches of a seedless cucumber
kosher salt, to taste
fresh ground pepper, to taste
3/4 - 1 cup mayonnaise, see note below

Preparation

Boil the potatoes in their skins until tender. Boil the carrot, unpeeled, in the same pot. Boil the egg until hard boiled at the same time.
In the meantime, slice the cucumber and the onion very thinly. Sprinkle both with a little salt, and let sit for a while (10 minutes or more) until the vegetables exude their juices. Squeeze firmly to get rid of the juices.
When the potatoes and carrot are done, drain and peel them while still hot (holding each in a kitchen towel to peel them helps). Smash the potatoes and shred the carrot. Mix in a little salt and pepper and leave to cool.
Peel the hard boiled egg and chop up finely.
When the potatoes and carrot mixture has cooled to room temperature, mix in the cucumber, onion and egg. Mix in the mayonnaise. Cover with plastic wrap and cool in the refrigerator until serving time (ideally at least one hour).
Note regarding mayonnaise: The ideal mayo to use is a Japanese one. Next best would be to make your own, using a flavor-neutral vegetable oil such as canola or safflower, not extra virgin olive oil. (\"Extra Light\" olive oil is fine.) Lacking access to Japanese mayonnaise or the time to make your own though, any commercial mayo will do as long as it's not too heavy on the vinegar flavor. Salad cream such as Miracle Whip should not be used however.