Toss the cucumber and onion in a little salt and drain for 15 mins.
Rinse off the salt and dry on paper towel.
Bring small saucepan of water to boil and hard boil eggs – maybe 6 - 8 minutes
Transfer eggs into iced water and tap the shells all over while in the water – this makes it much easier to peel the eggs.Peel and roughly chop
Cook sliced carrots in boiling water for 3-4 mins, cooked and not mushy.
Cook potatoes and peel while hot. Roughly chop and mash, season with salt – or not.
While potatoes are still warm – not steaming hot – add the vinegar, half the mayonnaise, cucumber, onion, carrot and eggs and mix together.
Taste and adjust seasoning if needed and add more mayonnaise if required. I personally use less than a cup of Kewpie.