Yaki Udon with Beef

Ingredients (serves 2):
250g beef, thinly sliced
1 tbsp light soy sauce
1 tsp mirin 1 tsp sake
1/2 tsp corn flour
Two portions of udon noodles
2 stalks of spring onions, sliced on the diagonal
2 bunches of bak choy or other greens, cut into sections
Oil for cooking
4 tbsp light soy sauce
2 tbsp sake
1 tsp thick dark soy sauce (or Japanese Worchestershire sauce)
2 tsp sugar
Pinch of salt
1/4 tsp sesame oil
1 tsp sesame seeds, toasted

Method:
1. Marinate the beef in light soy sauce, mirin, sake and corn flour for an hour or overnight.
2. Cook the udon noodles according to pack instructions. Drain and set aside.
3. While the noodles are cooking, heat a wok or large pan until hot and toast the sesame seeds in the dry pan. Stir to make sure they don't burn. Remove and set aside when lightly toasted.
3. Heat the wok again till it almost starts to smoke. Add some oil and when the oil is hot, add the beef. Stir fry briskly until the beef is half cooked, about 2 minutes. Set aside.
4. Heat more oil in the wok and add spring onions and boy choy. When the vegetables have just wilted, add the udon and the rest of the seasoning and mix well. Put the beef back into the wok to heat through and finish cooking. Dish out and sprinkle with sesame seeds to garnish.