Wang Fat Path Yuen Long has a heap of Indian, Halal, Indonesian and Nepalese grocery stores, as it services those communities living nearby, and the Gweilo's who have a bit of craving for authentic home cooked curries

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We live in Siu Lam which is about middle distance between where you are in Park island, about 15 minutes mini bus ride from here, so most likely about 25 to 30 minutes from where you are.
The other popular location to get Indian, Africaan and Middle Eastern groceries, is Chung King Mansions in Nathan Road, located in the block before you hit the Sheraton Towers Hotel side/end of TST.
You'll find what you are looking for in both locations.