Heat sugar in a heavy saucepan over medium-low heat until sugar becomes lightly brown. Slowly stir in soy sauce. Once the sugar and soy sauce are combined, stir in the water, star anise, curry leaves, ginger, and garlic. Increase heat and bring to a boil. Simmer until the sugar is dissolved, about 15 minutes.
Remove from heat and cool. Strain sauce and pour into a lidded bottle or jar. Store in the refrigerator.
