4 L water
2 loh hon goh (Buddha's fruit), wash and cracked open
10 tai hoi lam, washed and soaked
200g winter melon flesh, finely shredded
1/2 cup dried longans, rinsed
gula melaka (optional)
Tai hoi lam is an olive-like dried fruit. When soaked in water it expands more than double its size and the flesh is transparent and feels like jelly. The outer skin has to be discarded and that's the part I find most tedious in this whole process of preparing the tong sui. The skin can be easily detected when soak in water as they are opaque while the flesh is transparent. At the top of the bowl of soaked tai hoi lam you can easily see a small black triangle speck floating on the water - that's the skin to be discarded. This ingredient is used more for the texture than its taste. Strain away the soaking water and it is ready to be used.
Bring the winter melon, loh hon goh (skin and seeds) and water to a boil, lower heat and let simmer for 3 hours.
Fish out the loh hon goh and discard.
Add the sugars to taste. Turn the heat off.
Add the soaked tai hoi lam and dried longans. Let it stand for a minute and it is ready to be served hot.
Leave in the fridge and you can have icy cold tong sui whenever the weather get unbearably hot.