Combine orange zest, juice, soy sauce, vinegar, and cornstarch in a medium bowl; set aside.
In a large skillet on medium, heat 3-5 teaspoon oil. Cook pork pieces in oil 1-2 minutes, until browned on one side. Move to a plate and set aside; reserve skillet.
In reserved skillet add garlic and scallion whites. Cook 1-2 minutes until scallions wilt, stirring occasionally. Add broccoli and ½ cup chicken broth to skillet.
Cover and cook 2-4 minutes, until broccoli is crisp-tender.
Add pork and stir-fry sauce from step 1 to your skillet. Cook 1-2 minutes, stirring until pork is cooked through and sauce has thickened.
Top with scallion greens.