• Gather all the ingredients.
  

To Toast and Grind the Sesame Seeds

• Add 4 Tbsp toasted white sesame seeds to a dry frying pan. Toast over medium heat, holding the pan slightly above the burner and shaking it continuously so they heat evenly, about 3 minutes. When 2–3 seeds start popping, immediately remove the pan from the heat.

  Nami's Tip: Sesame goes from toasted to scorched in seconds, and scorched seeds turn the whole batch bitter.
  
• Grind the toasted sesame seeds in a Japanese mortar and pestle until coarse and fragrant. Stop while some seeds are still whole.

  Nami's Tip: Ground to a smooth paste, the dressing loses the texture that makes it worth grinding. A food processor works but grinds unevenly, so pulse and check often.
  

To Make the Dressing

• Add 4 Tbsp Japanese Kewpie mayonnaise, 2 Tbsp rice vinegar (unseasoned), 1 Tbsp sugar, 2 tsp soy sauce, and ¼ tsp toasted sesame oil to the mortar. Mix until combined.
  

To Chill (Optional)

• Transfer the dressing to an airtight jar and refrigerate for at least 20 minutes so the flavors settle as it cools.
  

To Serve

• Drizzle over a simple salad of iceberg lettuce, tomatoes, boiled eggs, wakame seaweed, and corn, or over shredded cabbage salad.
  

To Store

• Store the dressing in the refrigerator for up to a week.

  Nami's Tip: It thickens as it chills. Loosen it with a teaspoon of water and shake before serving.