½ cup sesame seeds, toasted
¼ cup soy sauce
2 tablespoons sugar
Kosher salt to taste
1 pound green beans
2 tablespoons rice vinegar
2 tablespoons finely chopped scallions
2 teaspoons minced fresh ginger
Finely grind the sesame seeds (in a mortar or a spice grinder if you have one, otherwise just use a food processor). Transfer to a food processor and add remaining sesame seeds, soy sauce, and sugar and process into a paste. Set aside.
Bring an 8-quart stockpot of salted water to a boil. Add green beans and cook until crisp tender about 4 minutes. Transfer beans to a large bowl of ice water to stop them from cooking further. Chill. Drain and dry green beans. Whisk vinegar, scallions, and ginger with reserved sesame paste in a bowl. Add beans and toss. Can be made ahead. Serve at room temperature.