Tub Tim Grob (Thai Red Rubies in Coconut Milk)
Prep time
Cook time
Total time
Yield: Serves 4
Coconut Milk
  • 500 ml coconut milk (preferably fresh, but canned or powder will work as well)
  • 3 to 5 pandan leaves, rinsed and tied into a knot
  • 2 to 3 tablespoons caster sugar, to taste
Sugar Syrup
  • ½ cup sugar
  • 1 cup water
Red Rubies
  • 25 water chestnuts
  • Red food colouring
  • ¾ to 1 cup tapioca flour
Coconut Milk
  1. Combine coconut milk and pandan leaves in a separate, clean pot and bring to a simmer. Simmer for 10 to 15 minutes to infuse it with the pandan flavour and add in sugar to taste. Remove from heat and set aside to cool completely. Remove the pandan leaves and chill the coconut milk in the refrigerator.
Sugar Syrup
  1. Combine sugar and water in a small pot. Bring to a simmer and stir until all the sugar has dissolved. Remove from heat and set aside until the syrup has cooled completely to room temperature.
Red Rubies
  1. Peel the water chestnuts. Halve each water chestnut horizontally to form 2 discs, then cut each disc into 6 pieces (12 pieces per chestnut). Transfer the water chestnut pieces into a bowl and add in 5 drops of red food colouring and 1 tablespoon of water. Stir with a spoon to colour the water chestnuts. If you think it's not red enough, add a few more drops of red food colouring. Set aside for 5 minutes.
  2. Bring a large pot of water to boil. Prepare a large bowl of ice water.
  3. Place ¾ cup of tapioca flour in a shallow bowl. Transfer the dyed water chestnuts into a sieve and drain away all the liquid (discard the liquid). Transfer the water chestnuts into the bowl of tapioca flour and toss with a spoon to ensure every piece is coated with tapioca flour.
  4. Scoop out all the water chestnuts into the sieve and tap gently to sift out excess tapioca flour. Spritz the water chestnuts all over with water, then return the water chestnuts back into the bowl of tapioca flour. Add in remaining ¼ cup tapioca flour if needed to coat the water chestnuts.
  5. Scoop out the water chestnuts again into the sieve and tap to sift out excess tapioca flour.
  6. Add the water chestnuts into the boiling pot of water (it must be boiling!) and stir for 30 seconds to prevent the water chestnuts from sticking to the bottom of the pot and from sticking to each other. Boil the water chestnuts, stirring occasionally, until they float on the surface of the water, which will take only a few minutes. The tapioca flour will form a chewy layer around the water chestnuts and become translucent, forming the red rubies.
  7. Remove the red rubies with a slotted spoon and immediately plunge them in the bowl of ice water to stop the cooking.
  1. If serving immediately, strain the red rubies and add them into the coconut milk and serve the syrup on the side. If not, strain the red rubies and add them into the syrup. Refrigerate them until ready to serve.
  2. Use a slotted spoon to scoop the red rubies into serving cup. Top with the chilled coconut milk and serve. Allow your guests to add in additional syrup (used to soak the red rubies) if desired.
Naggy Notes
- If you add the red rubies into the coconut milk, serve it as soon as possible because if left aside for too long, the red rubies will dye the coconut milk pink colour.

- Adapted from Thai Table
Recipe by Foodie Baker at https://www.foodiebaker.com/tub-tim-grob/