Sunomono

Steps

1. slice6 min
   2 mm rounds — a dime's thickness — with a keen knife, or a mandoline set thin but NOT at its finest
   cucumbers into even rounds, after peeling the skin away in lengthwise stripes if you want the striped shima-muki look, which also lets a little of the skin's bitterness out. Two millimetres is the target because that is thin enough for the vinegar to penetrate the whole slice and still leave it stiff enough to snap; a thick round never takes up the dressing, stays watery in the middle and tastes of almost nothing. The edge decides this. Cucumber exposes a dull blade more plainly than any other vegetable — a blunt edge crushes and tears the round rather than parting it, so the slice comes off the knife ragged and already weeping, and a torn round cannot survive the squeeze this recipe depends on. The finest mandoline setting causes the same failure from the other direction: slices that fine disintegrate in the hand. If the blade is skidding across the skin instead of dropping through it, that is the problem, not your technique.
2. season7 min
   1 tsp salt massaged through, left 5 to 10 minutes until translucent and slumped
   sliced cucumber + salt, tossed and rubbed with the fingers so every round is coated, then left alone. The salt raises the solute concentration outside the cell walls and water leaves the cucumber by osmosis to meet it — that is why the slices go glassy and lose their rigidity, and it is why they end up firmer rather than softer once the water is gone. Watch for the colour change: opaque green to translucent is the signal that the step has worked.
3. prep3 min
   squeezed firmly by hand, a small handful at a time
   gather the salted slices in the palm and press hard enough to run liquid out between the fingers, working in handfuls rather than one mass. Skipping this is the single most common way sunomono fails, and the failure is delayed rather than immediate: the water you leave in the cucumber comes out over the next twenty minutes, into the dressing, which arrives at the table thin and pale while the slices sit limp in a puddle. Rinsing before squeezing is optional and sources split on it — rinse and you remove salt the dressing was already accounting for, so taste before adding the dressing's own half teaspoon.
4. rest8 min
   dried wakame submerged in cool water, then squeezed dry the same way
   wakame + cool water, left 5 to 10 minutes until fully unfurled and tender, then drained and pressed out. Dried wakame swells eight or ten times over, so a single tablespoon that looks like a scattering of black flakes becomes a real handful of green — measure it dry and resist the urge to add more. It is squeezed for exactly the reason the cucumber is: soaked seaweed carries a surprising amount of water and it will dilute the dressing just as effectively.
5. mix3 min
   warmed only enough to dissolve the sugar, then cooled to room temperature
   rice vinegar + sugar + salt + soy sauce, stirred over the barest heat until no crystals are left, then taken off and cooled = amazu. Learn this as a ratio and not a list: equal volumes of vinegar and sugar, with salt and soy as accents, and it scales to any bowl. Use unseasoned rice vinegar — seasoned rice vinegar already carries its own sugar and salt, and it will throw the ratio off in both directions at once. Cool the dressing before it meets the cucumber; warm amazu wilts the slices you just spent three steps keeping crisp.
6. top2 min
   tossed and dressed within a few minutes of serving
   squeezed cucumber + wakame + cooled amazu, turned over lightly, then + toasted sesame seeds scattered over. Dress it late. Even properly squeezed cucumber keeps giving up water for as long as it sits in an acidic dressing, so the salad is at its best in its first ten minutes and slowly loses definition after that. Serve it cold, in a small deep bowl with some of the dressing spooned over rather than drained off — the liquid is part of the dish and is drunk from the bowl.