Add 2 tbsp toasted white sesame seeds to a large dry pan.
Toast the sesame seeds over a medium-high heat until fragrant and slightly golden. Shake the pan regularly and remove from the heat as soon as they're done to prevent burning.
Grind the sesame seeds using a mortar and pestle until you have a fine powder.
Pour the ground sesame into a container and add 2 tbsp Japanese mayonnaise, 1 tsp rice vinegar, 1 ½ tsp sugar, 1 tsp Japanese soy sauce (koikuchi shoyu) and 1 tsp toasted sesame oil.
Mix until well combined and enjoy!
Large batch (16 portions)
Toast 115 g toasted white sesame seeds in a large dry pan until golden and fragrant, then pour into a food processor and blitz until they become a powder.
Add 190 g Japanese mayonnaise, 40 ml rice vinegar, 35 g sugar, 40 ml Japanese soy sauce (koikuchi shoyu) and 40 ml toasted sesame oil. Blitz again until all the ingredients are evenly distributed.
Enjoy!
Notes
Store in an airtight container in the fridge for 1 week.The 2 servings batch doesn't work in a food processor since the amount is too small. I recommend a food processor for large batches.