Cook rice according to package instructions. Meanwhile, in a large skillet, heat oil over medium-high. Season steak with salt and pepper; cook 4 to 6 minutes per side for medium-rare. Transfer to a plate, and tent with foil (reserve skillet).
Place snap peas, asparagus, garlic, red-pepper flakes, and 1/4 cup water in skillet. Cook, tossing, until vegetables are crisp-tender, 3 to 5 minutes. Add soy sauce and vinegar; toss to combine.
Slice steak thinly across the grain. Serve steak, vegetables, and rice drizzled with pan juices.
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