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 70% 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 black fungus and add just enough hot water to cover 1/2 of 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.
Fresh lotus roots and black fungus (wood ear mushrooms) can be found in Chinese/Oriental speciality stores.
If fresh lotus roots are unavailable, substitute in the tinned variety.