Combine orange zest and juice, soy sauce, honey, garlic and pepper flakes in a bowl.
Combine beef and 1/3 cup orange juice mixture in a 12" non-stick skillet. Cook over medium-high heat until liquid has evaporated and beef is caramelized, about 15 minutes. Transfer the beef to a plate and tent loosely with aluminum foil.
Add the remaining orange juice mixture and the snap peas to now-empty skillet and cook, covered, over medium heat until the snap peas are bright green, about 2 minutes. Uncover and continue to cook, stirring occasionally, until the sauce thickens and the snap peas are tender, about 1 minute. Return the beef to the skillet and toss with the snap peas to combine. Transfer to a platter and sprinkle with scallions. Serve.