Toss the beef slices in the soy sauce, then the cornstarch to coat. Place in the freezer to chill while you ready the sauce.
In a medium bowl, combine the rice vinegar, orange juice, sesame oil and brown sugar. Stir to combine and set aside.
In a dry pan over low-medium heat, toast the chile flakes, orange rind, and ginger until the orange is fragrant. Add ½ TB peanut oil and the garlic and stir, cooking until the garlic starts to lighten in color. Pour in the rice vinegar mixture, and stir to combine.
Let the sauce reduce and thicken, stirring often, until it is syrupy and coats the back of a serving spoon (about 3-5 minutes.) Remove the sauce from heat and pour into a medium bowl and set aside. Clean the pan and return it to the stovetop. Heat the remaining 1/4 cup peanut oil over medium heat until shimmering. Take the beef out of the freezer and add to the oil slice by slice, leaving a little room between each. Work in batches if you need to. Cook the beef until the first side is browned and crispy, then turn and do the other side. Place the cooked slices on a plate lined with paper towel to soak up any excess oil. Toss the cooked beef slices in the sauce until coated, then serve immediately over rice. Garnish with diced scallions.