• Gather all the ingredients.
  

To Make the Dressing

• 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 (I use this whisk). Once the sugar dissolves completely, remove from the heat and let it cool. Tip: If you decrease the sugar amount (which I don't recommend), you may find that the vinegar tastes too strong. If it's still too strong for you after adding the cucumbers, you can dilute it at this stage with a very small amount of Dashi (Japanese soup stock), Vegan Dashi, or water.
  

To Make the Sunomono

• Soak 1 Tbsp dried wakame seaweed in a bowl of water and let it rehydrate for 5 minutes.
  
• Meanwhile, peel the skin of 2 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. The salt draws out the moisture from the cucumbers so it doesn't dilute the dressing later.
  
• 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.
  

To Make the Variations

• Crabmeat: Cut 4 pieces real or imitation crabmeat into thirds lengthwise. Add to the cucumber and wakame seaweed mixture in Step 7. 

  Boiled octopus: Slice 2 oz octopus sashimi (boiled octopus) thinly. Add in Step 7. 

  Boiled salted baby anchovies: Add 2 Tbsp shirasu (boiled salted baby anchovies) in Step 7.
  

To Store

• Keep in an airtight container and store in the refrigerator for up to 3 days for the classic version and 2 days for the seafood variations. However, the cucumber may release more moisture and dilute the sauce, so enjoy it soon!