Freeze beef until firm, about 1 hour (to slice easier). Thinly slice, then arrange on a paper towel lined baking sheet and chill 20 minutes.

Meanwhile, bring water and rice to a boil in a saucepan. Reduce heat to medium-low; simmer, covered, about 20 minutes, until tender. Whisk together sugar, rice vinegar orange juice concentrate, soy, and salt in a small bowl.

Coat beef with cornstarch, shaking to remove excess. Heat oil in a wok over medium-high heat. Work in batches, fry beef until crispy and golden brown, about 2 minutes per batch. Transfer to paper towel lined plate.

Drain all but 1T oil from the wok. Stir in ginger, garlic, and orange zest; cook, stirring, until fragrant, about 30 seconds. Add soy sauce mixture and bring to a boil. Cook until thick and syrupy, about 5 min. Add beef, stirring to coat, and cook until heated through. Serve over rice and vegetable. Garnish with zest and sesame seeds.