Take the hollowed-out cucumbers and chop them roughly. Toss
them into a blender with ½ cup water and a big pinch of salt and
blend just to break them down (you want a chunky mixture).
Strain the mixture through a sieve—pressing hard to release all
the cucumber juice—and taste for seasoning.
To serve, pour cucumber juice into each serving dish and place a
few jalapeño rings in the liquid along with a few pickled cucumber
rods. Place a scoop of crab on top of each dish, sprinkle with
togarashi, and, if you have it, garnish with a spoonful of trout roe.
* Togarashi is a Japanese condiment with a spicy, citrusy kick,
made with orange peel, sesame seeds, cayenne, ginger, Szechuan
pepper, and nori.