Heat a small sauce pot over medium heat. Add 1 teaspoon of sesame oil, ginger, garlic and scallion whites. Sauté for 1 minute. Add the chicken broth, remaining 2 tablespoons soy sauce, sriracha, and hoisin and whisk to combine. Add the remaining 1 tablespoon cornstarch and whisk sauce until starting to thicken, about 2 minutes. Once thickened, turn heat to low and keep warm while you make the chicken.