Marinate beef in soy sauce, cornstarch, and half the orange juice for 30 minutes to 1 hour.
Whisk together remaining orange juice, orange zest, marmalade, brown sugar, and rice wine vinegar for sauce. Set aside.
Heat oil in a large skillet or wok over high heat.
Fry marinated beef until golden brown and crispy on all sides. Remove and drain on paper towels.
Pour sauce into the same pan and simmer for 2-3 minutes until slightly thickened.
Add crispy beef back to pan and toss to coat well with sauce.
Serve immediately over rice and garnish with sesame seeds and chopped green onion.