Blanch the spinach in boiling water for 30 seconds, then shock in ice water, strain and squeeze out the excess water with your hands.

Chop the spinach into 2-inch pieces and set aside.

Pulse the toasted seeds in a food processor until partially ground.

Combine the sesame seeds with the tamari, sugar, sake and mirin and toss with the spinach. Serve at room temperature or chilled.