Foryoueats: Chicken Teriyaki

Ingredients

• 1 cup soy sauce
• ¾ cup sugar
• 2 tablespoons mirin
• 2 teaspoons Asian sesame oil
• 2 tablespoons coarsely chopped fresh ginger from a 2-inch knob
• 4 cloves garlic coarsely chopped
• ¾ cup water divided
• 3 pounds boneless skinless chicken thighs, trimmed
• 1 tablespoon cornstarch
• 3 scallions dark green parts only, for serving
• 1 tablespoon sesame seeds for serving