Combine the sweet chilli sauce, lime juice, brown sugar and fish sauce in a jug. Set aside.
Slice the snow peas lengthways. Blanch in a saucepan of boiling water for 1 minute or until just tender and bright green. Refresh in cold water. Drain well and transfer to a large bowl.
Slice capsicum and carrot into thin strips and combine with snow peas, onion, rocket, mandarin and coriander sprigs (reserving a little for garnish).
Preheat a chargrill or frying pan over medium heat. Add oil to frying pan or brush over chargrill. Add steaks and cook for 4 minutes on each side for medium-rare or until cooked to your liking. Transfer to a plate and stand for 10 minutes.
Thinly slice beef on an angle, then add to salad and toss to combine. Transfer to serving plates. Drizzle with the dressing and garnish with the reserved coriander sprigs. Serve.