Cook the rice noodles according to package directions, drain and rinse with cold water.
Sprinkle the steak slices with salt and pepper and heat 1 tablespoon oil in a heavy frypan. Fry the steak about 4 minutes, until just browned.
In a salad bowl, combine steak, noodles, lettuce, red onion, cucumber and Thai chilli. Mix together the lime juice, sugar and fish sauce until the sugar has dissolved and pour over the salad. Toss and garnish with torn Thai basil leaves.