Put the spring onion, ½ tbsp vinegar and the juice of ½ lime in a bowl. Add the mango and turn to coat. Set aside.
Meanwhile, brush the steak with 1 tbsp sesame oil and season well. Set a large frying pan over a medium-high heat. Cook the steak for 5 minutes, turning every minute, or until done to your liking. Transfer to a plate, cover loosely with foil and leave to rest for 10 minutes.
In a bowl, whisk together the fish sauce, honey, chilli, garlic, ginger and remaining vinegar and lime juice.
Cook the rice according to pack instructions. Keep warm.
Set a frying pan with the remaining oil over a medium-high heat. Add the sugar snaps and bean sprouts and cook for 1 minute. Pour over the dressing, toss and cook for another minute. Thinly slice the steak. Stir into the sugar snaps with half the mint.
Divide the rice between two bowls and top with the beef and pickled mango. Scatter over the remaining mint and the cashews to serve.