Whisk hoisin, soy sauce, cornstarch, chili-garlic sauce, and orange zest and juice together in small bowl. Measure 1 tablespoon sauce mixture into medium bowl, then add chicken and 1 teaspoon oil. Cover and marinate chicken in refrigerator for at least 10 minutes or up to 30 minutes.

Cook broccoli, bell pepper, and water covered in large saucepan over high heat until water is boiling and vegetables begin to soften, about 4 minutes. Uncover, continue to cook until water has evaporated and broccoli is lightly browned, about 2 minutes more. Transfer to platter. Add remaining 1 teaspoon oil to now-empty saucepan and return to high heat.

Add garlic mixture to center and cook, mashing mixture into skillet until fragrant, about 30 seconds. Stir garlic mixture into skillet. Add garlic cloves and ginger to skillet. Cook, stirring constantly, until sauce is thickened, about 1 minute. Transfer to serving platter, sprinkle with scallion, and serve.