Cut the radishes into thin strips, mix with the mint, chop everything together finely, season lightly with salt, marinate in a bowl with oil and juice of one lemon.
Blend the cucumber pieces with the milk, crème fraîche, wasabi, water, a dash of juice from one lemon and a tiny bit of salt until nice and fine. Fill into small shot glasses (shooters). Pile the marinated radish-mint mixture on top of the cucumber shooter.