In a large stock pot, add beef, ginger, garlic, cinnamon stick, star anise and rock sugar.
In a small bowl, combine sauce ingredients and pour the sauce evenly over the beef.
Add enough water to just cover the ingredients.
On high heat, bring the pot to a boil. Turn the heat down to low, cover and let simmer for 1½-2 hours until the meat is tender.
Skim off and discard some of the fat that has floated to the top, if desired.
In a small bowl, dissolve cornstarch in water and stir the slurry into the sauce. Heat through until the sauce thickens.