Thai Red Rubies Dessert (Tub Tim Grob) — Jump to:Step-by-Step Photos · Recipe

Tub Tim Grob (ทับทิมกรอบ) is a Thai dessert that consists of little red rubies (edible of course!) made with water chestnuts and tapioca flour, served with sweetened coconut milk and ice. It is a sweet, refreshing and delicious dessert – just the perfect treat for the summer!

How are the red rubies made?

Peeled and diced water chestnuts are coated with red food colouring, dipped in tapioca flour then boiled in water – the tapioca flour creates a reddish and translucent coating around the water chestnuts, and because of the red food colouring, they look just like red rubies, don’t they?

Fresh vs Canned vs Powdered Coconut Milk

I would have used fresh coconut milk but it’s impossible to get them here. ): I’ve tried using both canned and powdered coconut milk before for this dessert and they work just fine. And if possible, don’t skip the pandan! Infusing the pandan flavour into the coconut milk is just amazing. I brought back a huge bunch of pandan leaves from Singapore when I went back in December, rinsed the leaves and freeze them in small bundles so I can use them whenever I want.

I absolutely love how the red rubies are crunchy (water chestnuts) and slightly chewy (tapioca flour coating) at the same time. Served chilled with coconut milk makes this the one of the best dessert to enjoy during summer! If you don’t want to make the pandan-infused coconut milk, why not try having these beautiful red rubies with my no-churn coconut ice cream? Equally yummy I believe! Here’s how to make this delicious Thai dessert!

Step-by-Step Photos

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.	2) Halve each water chestnut horitzontally to form 2 discs, then cut each disc into 6 pieces (12 pieces per chestnut).

3) 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.	4) Place 3/4 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).

5) Transfer the water chestnuts into a bowl of tapioca flour and toss with a spoon to ensure every piece is coated with tapioca flour.	6) Scoop out all the water chestnuts into the sieve and tap gently to sift out excess tapioca flour.

7) Spritz the water chestnuts all over with water, then return the water chestnuts back into the bowl of tapioca flour for a second coating. Transfer into a sieve and sift out excess tapioca flour.	8) 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.

9) Boil the water chestnuts, stirring occasionally, until they float on the surface of the water, which will take only a few minutes.	10) Remove the red rubies with a slotted spoon and immediately plunge them in the bowl of ice water to stop the cooking.

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