Bring a large pot of water with the pinch of salt to a boil. Place a large bowl of ice water near the pot.
Add the kale and cook just until vibrant and tender, 30 seconds to 1 minute.
Transfer the kale to the bowl of ice water and set aside.
Use a Suribachi and Surikogi or mortar and pestle to grind the sesame seeds and sugar until crushed.
Transfer the crushed sesame seeds and sugar to a large bowl and mix in the soy sauce and mirin.
Squeeze out the excess moisture from the kale and cut into even, 2 inch (5 centimeter) pieces.
Place the kale in the bowl with the sesame seed mixture and use your hands, a spoon, or chopsticks to bring the ingredients together until evenly coated and combined.
Serve immediately or refrigerate in an airtight container for up to three days.