- Whisk together teriyaki sauce, water, sesame oil, brown sugar and cornstarch in a medium saucepan until cornstarch is dissolved. Heat over medium-low heat until simmering. Simmer for 1-2 minutes, until sauce has thickened and brown sugar is dissolved. Remove from heat and pour sauce into a small bowl to cool for 10 minutes.
- Heat oven to 400ºF and line a medium baking sheet with parchment paper. Combine Brussels sprouts and ½ of cooled teriyaki sauce in a medium mixing bowl. Spread evenly on baking sheet.
- Roast for 15 minutes. Stir and roast for 10-15 minutes longer depending on the size of Brussels sprouts. Remove from oven and serve hot topped with remaining sauce and toasted sesame seeds.