Place the steak, half the soy sauce, the garlic and 2 tablespoons of the lime juice in a large bowl and allow to stand for 10 minutes.
Cook the steak on a preheated grill pan for 1 to 2 minutes each side. Put aside.
Steam the broccoli in a steamer or colander set over a saucepan of boiling water for 5 to 6 minutes or until crisp-tender. Allow to cool for 10 minutes, then combine with the mint, basil, coriander and cucumber.
Slice the steak and add to the broccoli mixture. Combine the chillies, sugar and the remaining soy sauce and lime juice. Pour over the steak and broccoli, folding gently. Pile the salad onto serving plates.