Make the marinade by mixing together the sugar, soy sauce and cornflour slurry. Mix in the beef, allow to marinate for 15 minutes.
Heat a large frying pan with 1 tablespoon oil. Stir fry the garlic until aromatic, 2-3 minutes. Add the beef, stir fry until nearly done, about 3-4 minutes, set aside.
Heat the same frying pan with 1 tablespoon oil. Stir fry the lotus root for 2-3 minutes or until lightly browned. Add the wood ear mushrooms and just enough hot water to half cover the ingredients. Cover the frying pan and simmer for 3-5 minutes. Continue to simmer until there is very little liquid let, about 3-5 minutes.
Add the beef back into the pan and mix well. Stir in the oyster sauce to taste and serve.