Cut Kabocha into small pieces and place in a microwave-safe dish. Cover and cook about 6 minutes in the microwave oven or until soft. Remove skins and mash Kabocha (you don't need to mash all the way if you want it chunky).

Slice cucumber thinly and sprinkle with salt in another bowl. Let it sit for a few minutes and squeeze water out.

Mix Kabocha, cucumber, lemon juice and mayonnaise. Salt and pepper to taste.