Peel, halve and core the cucumber, then cut into slices, season with salt and mix. Now drain in a sieve for about 40 minutes.
Rinse the salt in water, pat the cucumber dry, puree and squeeze it out in a clean cloth.
Cook the potatoes unpeeled in salted water, let cool down a little, peel and mash them. Now heat it up again in a large pan, stir in the heated cream, mix in the butter and coriander well and season with salt and pepper mixture to taste.
Warm up the mashed potatoes again immediately before serving and mix with the cucumber puree.