Heat the oven to 200°C (400°F), Gas Mark 6.
Mix the marinade ingredients together. Toss the beef in the mixture then coat in the sesame seeds. Place in a baking dish and cook for 30-40mins for rare and an extra 10 for medium and 15 for well done. Allow to rest for 20 minutes before slicing.
Mix the dressing ingredients together in the processor. Stir half the dressing through the noodles and set aside.
Slice the extra scallions and chilli into finger sized strips and leave in iced water until ready to serve. Slice the beef thinly and garnish with the scallions and chilli and serve with the noodles and the remaining dressing.