Cut beef shin
into small pieces and cook over low heat with 800ml water till meat is
tender. Reduce beef stock to about 500ml. Set aside.
* Finely grind
galangal, garlic, shallots, dried chilies and turmeric. Combine water,
cornflour and mashed sweet potato then mix well. Set aside *.
Heat 4 tbsp oil
in wok till hot. Stir-fry ground ingredients (*) till fragrant. Add soy
bean paste and mix well. Add beef stock and bring to boil again. Season
with sugar and salt. Stir in cornflour mixture (*) to thicken gravy.
Divide noodles and bean sprouts into plates. Spoon gravy over and top with
garnishing. Serve hot.