Thai Red Rubies Dessert (Tub Tim Grob, Thapthim krop, ทับทิมกรอบ, 椰香红宝石)



My kids went holiday to home town and their aunties brought them to a Thai restaurant..They ordered the Thai red ruby dessert and obviously very impressed with that.. They told their aunties that it is very nice and wanted to ask their father to do it… My sister in law messaged me and asked me if I am able to do this dessert.. I told them, no problem as it is a rather simple recipe..


When they are back home few days ago, I have decided to lay my hand to do the dessert.. I prepared early in the morning and when they woke up from the bed, they are so happy to see the dessert is ready.. It is also a joy to see them “wow here and there” seeing the food that they liked.. ha-ha.


I am sure this is not an unfamiliar dessert to most readers. Initially, I thought that it is very difficult to prepare when I first tasted it many years ago in the Thai restaurant. The dessert looked very complicated since it is a piece of water chestnuts wrapped in some transparent tapioca dough. Initially, I thought that I have to make a red dough and wrap the small white water chestnuts one by one…


But I was wrong, totally wrong, all my speculations were wrong.. After viewing one video in the internet, i found that the process is much easier . Water chestnut was cut, coloured and “coated” by using tapioca flour rather tapioca flour dough.. Well, I did not follow exactly that recipe since this is a very simple flexible recipe and error tolerances are very high.. Therefore, for readers, I will share the methods and feel free to add or minus quantities of the ingredients as stated in the recipe.


“Thapthim krop (Thai: ทับทิมกรอบ, pronounced [tʰáp.tʰīm krɔ̀ːp]) is one of the most famous Thai desserts, which is made of cubes of water chestnuts in syrup coated with red food coloring. This dessert is known as “pomegranate seeds” or “rubies” because of its appearance.[2] It is usually eaten with coconut milk and ice cubes.”



Servings: About 8-10 adult servings


Water Chestnuts Coating

  • 500 grams of water chestnuts, de-skinned
  • 250 grams of tapioca flour
  • About 1 tablespoon of red colouring

Coconut milk syrup

  • 600 grams or ml  of thick coconut milk
  • 600 grams or ml of plain water
  • 150 grams of castor sugar
  • 10 pandan leaves, tie into knot
  • Pinches of salt




PicMonkey Collage1

  • Put all the coconut milk syrup ingredients in a pot and bring to boil under medium to high heat. Constant stirring is required to avoid lumps being formed. Once done, take out the pandan leaves and let it cool completely. If preferred, chill in the fridge.  If it is too sweet, you can add more water but remember that water chestnut will be tasteless.

  • Put the red colouring and add additional a few tablespoons of water. Cut the water chestnuts into about 1 cm x 1 cm x 1 cm size (note that this is ideal and of course there will be head and tail that cannot follow the size which is ok as it will not be obvious). Put the cut water chestnuts into colouring water and let sit rest for at least 15 minutes or longer .


Colouring quantities is for your reference and it depends on your personal preference. In addition, it will varies with different brand, liquid gel vs liquid or powder form. So use your judgement and get the colour that you preferred.

PicMonkey Collage2

  • Once the water chestnut reached the colour tone you preferred, drain and pour the coloured water chestnuts into the tapioca flour. Use a spoon or fork to fold the flour onto the water chestnuts such that all the water chestnut is evenly coated. The coating shall be until an extent that the water chestnut cubes looked whitish . If it is pinkish, more tapioca flour need to be added. Let it rest for 15 minutes before the boiling.

  • Meanwhile, get ready another pot of icy cold water adequate to put all the cooked water chestnut.

PicMonkey Collage3

  • Get ready a big pot of hot boiling water. Once the water is boiling, add in the floured water chestnut cubes. The water chestnuts cubes will sink to the bottom of the pot and once it floated up, it is generally considered as cooked. However, as an additional cautious measure, looked for any cubes that is whitish in colour and ensure that all the cubes are transparent. Transfer the floated water chestnuts cubes to the icy cold water and let it rest for about 5 minutes. Drain and transfer to a container for future serving. Add some cooked water to avoid the cubes stick to each other.

  • For serving, in a serving cup, put one or two tablespoons of water chestnuts, put adequate chilled coconut syrup and best served as a dessert. If you preferred, you can add shelved ice to the dessert.




Let’s be very frank, if you are not into colouring, this dessert will not be suitable to you… But is it not the same when you ordered in the restaurant? However, it you do not mind to have another colour, I can suggest that you use blue pea flower for blue coloured water chestnut. That it will be blue ruby which is equally interesting…


Hope you like the post today. Cheers and have a nice day.



(updated as at 13 March 2015)  here and you can follow me at PINTEREST or visit the blog’s FACEBOOK PAGE to keep abreast of my future posts. Also follow me at INSTAGRAM or TSU, a new social network for some more personal sharing other than recipes.


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