Toast sesame seeds in a nonstick skillet over medium-low heat until fragrant and lightly golden brown. Stir frequently to avoid burning.
Let toasted sesame seeds cool down slightly, then grind them up with a mortar and pestle.
Transfer ground sesame seeds to a small mixing bowl. Whisk in soy sauce, monk fruit erythritol sweetener, mirin and sake until combined. Set aside.
Prepare an ice bath, and bring a large pot of water to a boil.
Add spinach to boiling water and cook for 30 seconds. Drain and dunk in ice bath immediately to stop the cooking.
Drain spinach and squeeze out as much excess liquid as you can with your hands.
Roughly chop spinach into smaller pieces.
Mix spinach with sesame sauce until combined. Serve warm or cold. Enjoy!