For the marinade: combine soy sauce, fish sauce, sesame oil, garlic, olive oil, lime juice and pepper in a large zip-lock plastic bag and mix well. Add beef, seal bag and marinate in the fridge for as long as you can, at least 30 minutes, turning the bag occasionally.
Heat a non-stick frying pan over medium-high heat until hot. Cook steak for 3 minutes each side for medium rare or until cooked to your liking. The beef should still be pink in the center (or to taste). Transfer to a plate, cover and leave to rest for several minutes.
Prepare the noodles according to package directions. Then drain and set aside.
Combine the dressing ingredients together and mix until the sugar has dissolved.
Evenly divide the noodles, salads, tomatoes, basil, coriander, red onion and chilli into four plates. Cut the cooked steak into thin slices on the diagonal and top over vegetables. Drizzle over the dressing and mix together well. Serve immediately.