Fill a large pot with water and bring to a boil over high heat.
Blanch the spinach for about 30 seconds until bright green.
Drain in a colander under cold running water for about 1 minute.
Squeeze the spinach into a ball to remove excess water and set aside.
Place sesame seeds in a food processor with a metal blade.
Pulse for about 1 minute until they reach the consistency of cornmeal (do not grind too fine).
In a large bowl, mix the ground sesame seeds, sugar, soy sauce, and sesame oil. Add the spinach and gently toss until evenly coated. Transfer to a platter and serve.