Put the steaks in a preheated hot griddle pan and cook for 3–4 minutes on each side. Allow to rest for 10–15 minutes, then slice the meat thinly.
Meanwhile, cook the sweetcorn in boiling water 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. Cut the cucumber into 5 mm (¼ inch) slices.
Put the beef, sweetcorn, cucumber, onion and chopped coriander in a large bowl. Stir in the vinegar and chilli sauce and mix well. Garnish the salad with sesame seeds and serve.