Jab the meat with fork several times on both sides. Place the in a large resealable bag, add the zest, half of the scallions, ginger, garlic, sugar, soy sauce, pepper flakes, tangerine juice, and sesame oil. Refrigerate overnight for better result.
Preheat a large cast iron skillet over medium high heat. Add oil and shake off some of the marinade ingredients, (reserve the marinade sauce) sear the steaks on both sides about 3 to 4 minutes or longer if you like well done.
In a small saucepan, boil the sauce for 3 to 5 minutes. Add the marmalade and stir. Cook for another minute.
Slice the meat against the grain and garnish with the remaining scallions. Serve with the sauce.
Recipe by The Gluten Free at https://www.theglutenfree.com/gluten-free-tangerine-beef-with-scallions/