For the Marinade:
1. Place all marinade ingredients into a bowl and mix.
2. Add sliced beef fillet into marinade. Cover and set aside to marinade for a few hours (overnight).
1. Heat a medium size pan/wok over high heat. Add olive oil until smoking hot.
2. Remove beef from the marinade and add to hot pan. Leave beef in pan to crisp up (do not shake around).
3. After 5-7 mins beef should be medium to rare. Add the Udon noodles and any leftover marinade to pan, stir through and top with sprigs of fresh coriander.
1. Remove from heat and place into serving bowl, top with fresh chilli, coriander and a squeeze of lime juice. Finish with handful of cashew nuts.