Put the steaks on a preheated hot griddle pan and cook for 3—4 minutes on each side. Allow to rest for 10—15 minutes then slice thinly.
Put the sweetcorn in a saucepan of boiling water and cook for 3—4 minutes or until tender. Refresh under cold water and drain well.
Slice the cucumber in half lengthways, then scoop out and discard the seeds using a small spoon. Cut the cucumber into 5 mm (¼ inch) slices.
Put the onion in a large salad bowl with the beef, sweetcorn, cucumber and chopped coriander. Stir in the rice wine vinegar and chilli sauce and mix well. Garnish the salad with lightly toasted sesame seeds and serve.