Wash and peel cucumbers . If you want can retain peels. If the seeds are tender retain it and chop cucumber into fine pieces as shown in the pic. However, if the seeds are matured and overgrown, scoop out the seeds, discard them and finely chop only cucumber part.

Grind coconut, mustard, salt and green chillies into a very fine paste adding required amount of water.

Transfer chopped cucumber into a bowl. Add ground masala into it.

Add curd and mix it nicely. Add more water/curd to get the desired consistency like a raita / gojju .

For seasoning heat 2-3 tsp of coconut oil / any oil in a ladle. Once hot add mustard, urad dal .. splutter. Add broken red chillies and few curry leaves. Turn off the heat and pour the tempering into cucumber sasive .

That's it cucumber kayi sasive is ready to relish with rice.