Cut the cucumber into quarters lengthwise so you have 4 long strips. Use the side of the knife blade and gently press down to smash the strip. It should be slightly deformed but not flattened.

Cut each smashed strip into pieces that are roughly as long as they are wide and tall. Place the cucumber pieces in a bowl.

Combine the sauce ingredients in a bowl. Stir until consistency is even. Pour sauce over smashed cucumber pieces. Stir to mix well. Garnish with sesame seeds. Add extra chili oil as desired. Serve chilled or at room temperature.

Place the dried fueru wakame in a medium-sized bowl and add at least 1.5 cups of water. Stir. Soak until fully rehydrated, about 10 minutes.

While the wakame rehydrates, slice the cucumber into round pieces as thinly as possible. Place the cucumber slices in a bowl and add the coarse salt. Stir to mix thoroughly, taking care not to break any of the cucumber pieces. After 5 minutes place the cucumber slices in a mesh strainer and squeeze out whatever liquid you can. Discard any liquid left in the bowl. It also helps to wrap the cucumber slices in a paper towel and gently squeeze to further dry the cucumber.

Drain the wakame and combine it with the cucumber slices in a bowl. Drizzle the sauce over the vegetables and stir to mix well. Garnish with sesame seeds, radish slices, and radish sprouts. Add extra chili oil as desired.