Gather all the ingredients.
In a saucepan, combine 4 Tbsp rice vinegar (unseasoned), 2 Tbsp sugar, ½ tsp Diamond Crystal kosher salt, and ½ tsp soy sauce. Alternatively, you can use a microwave-safe bowl and heat it in the microwave until the sugar dissolves.
Place the saucepan over medium heat and whisk the ingredients together well. Once the sugar dissolves completely, remove from the heat and let it cool.
Soak 1 Tbsp dried wakame seaweed in a bowl of water and let it rehydrate for 5 minutes.
Meanwhile, peel the skin of 2–3 Japanese cucumbers alternately to create a striped pattern. Then, thinly slice the cucumbers into rounds.
Sprinkle 1 tsp Diamond Crystal kosher salt on the cucumber and gently massage it in. Set aside for 5 minutes.
Use your hand(s) to squeeze out the liquid from the rehydrated wakame seaweed and add it to a medium bowl.
Squeeze out the liquid from the cucumber slices. Add them to the bowl with the wakame.
Add ½ Tbsp toasted white sesame seeds and pour the dressing on top.
Toss to combine everything together. Serve in individual bowls or a large serving bowl.
