Heat 1 tbsp oil in a wok over high heat, add egg and cook, stirring constantly, for 1 minute or until just cooked, transfer to a plate and set aside. Wash wok under hot water and dry.
Heat remaining oil in wok over medium-high heat, add mushroom and stir-fry for 1 minute. Increase heat to high, add asparagus and stir-fry for 30 seconds, then add rice and egg and stir-fry for 2 minutes, add soy, toss to combine and season to taste with sea salt. Stir through onion, add a few drops of sesame oil and serve.