Mix shallots, ginger and belacan in blender and grind until fine. Put the thin coconut milk in pot and add all ingredients except the thick coconut milk and seasoning. Simmer for 20 minutes, stirring occasionally.
Add the thick coconut milk, salt and sugar. Continue simmering until it thickens. Adjust seasoning and add more sugar if it is too spicy. Serve.
If you wish to make this into a main dish, you can add chicken or beef with some potatoes and tomatoes to this gravy.