Peel the water chestnuts and soak them in a bowl of water with a pinch of salt. Prepare the coloring: Wash the pandan leaves, blend, and strain to get the juice. Extract juice from gac fruit (or beetroot for red color). Cut the water chestnuts into small cubes and divide into three equal portions. In a pan, sauté one portion of water chestnuts with 1 tablespoon sugar until the sugar dissolves. Transfer to a bowl—this will be the white (uncolored) water chestnuts.

Repeat the sautéing process for the other portions. Color one portion green with pandan juice and the other red with gac fruit (or beetroot) juice. Once the sugar is absorbed, strain the colored water chestnuts to remove excess liquid and set aside in small bowls.

Place each portion of water chestnuts in a bag with 2 tablespoons tapioca starch. Shake well to coat evenly, then sift to remove excess starch. Repeat for the pandan and gac-colored water chestnuts. When coating the colored water chestnuts, add a little of the reserved coloring juice to intensify the color.

Bring a pot of water to a boil. Drop in the coated water chestnuts by color. When they float to the surface, remove and place them in a bowl of cold water to set the chewy tapioca coating.

Boil the lotus seeds until tender, then simmer with sugar (if using candied lotus seeds, you can skip this step). Bring 2 1/2 cups water (about 600 ml) to a boil, add sliced ginger. Dissolve 2 tablespoons (about 20 grams) tapioca starch in a little water, then slowly add to the boiling water while stirring. Add the remaining sugar to taste. Add all the water chestnuts, lotus seeds, and shredded young coconut. Stir and bring to a boil, then turn off the heat.

In a separate pot, cook the coconut milk with a little tapioca starch and a pinch of salt, stirring until slightly thickened. To serve, ladle the sweet soup into bowls, drizzle with coconut milk, and sprinkle with toasted sesame seeds and roasted peanuts. This dessert is delicious served hot or cold.