Red Rubies Dessert (Tub Tim Grob)

Sweet, creamy, and refreshing, this Thai red rubies dessert known as tub tim grob is perfect for a hot, summer day. The red rubies are chewy on the outside and crunchy in the middle, giving this dessert a wonderful and unexpected texture. Served with cold, sweet coconut milk, it's as beautiful as it is delicious.

I was captivated by this Thai red rubies dessert from my very first taste of it. I love most Thai desserts that are served with sweetened coconut milk (like this Pumpkin in Coconut Milk). But this one is particularly special. The "red rubies" have such a unique texture -- delightfully gummy on the outside, much like boba, but with a surprisingly crunchy center.

The first time I ate this dessert, I don't think I would have guessed that it's made from water chestnuts. Indeed, the bite-sized red rubies are made by coating small pieces of water chestnut with tapioca starch. Once they are boiled and cooled, they magically transform into delightful little gems that are chewy on the outside and crunchy in the middle. Paired with sweet, cold coconut milk, they make a unique, delicious, and very pretty dessert.

Why is it called Red Rubies Dessert?

In Thai, this dessert is known as Tub Tim Grob. Tub Tim is the Thai word for "ruby" (as well as "pomegranate seed", presumably because they look like rubies). Grob means "crunchy". So this dessert literally translates to crunchy ruby or crunchy pomegranate seed. Since the rubies are red, it's not much of a stretch to call this dessert Red Rubies in English.

Ingredients

• Water chestnuts: For this dessert, you can use either fresh or canned water chestnuts. If you are using fresh water chestnuts, you'll want to cut the top and bottom off, then peel the remaining skin off. Then proceed with either variety by cutting them into bite-sized pieces.
• Red food coloring: The bite-sized pieces of water chestnut are soaked in red food coloring to give them their distinctive ruby red color. If you prefer natural coloring, you could try beet root or pomegranate juice.
• Tapioca starch: Tapioca starch is what transforms these water chestnuts into beautiful gems. It can be found at Asian grocery stores and online. Other flours or starches cannot be substituted.
• Granulated sugar: White sugar is used to sweeten the coconut milk. Palm sugar could be used, if you prefer, although it will turn the coconut milk a darker color.
• Coconut milk: Coconut milk forms the base of this dessert, so it's important to use a good quality milk. Fresh, homemade coconut milk would be ideal, but canned works as well. The coconut milk is traditionally flavored with pandan leaves.
• Crushed ice: The dessert just isn't the same without crushed ice.

NOTE: This red rubies dessert is sometimes also served with small slices of tropical fruits or other jellies. Jackfruit, young coconut meat, lychee, longan, and toddy palm are common choices.

How to Make Red Rubies Dessert

1. Prepare the Water Chestnuts: If using fresh water chestnuts, cut the top and bottom off and peel them with a vegetable peeler. If using canned, simply rinse. Cut each water chestnut into very small bite-sized pieces (~¼" cubes).
2. Add the Red Color: Mix 20 drops red food coloring with a little water. Coat the water chestnut cubes in the food coloring mixture and let them sit for about 10 minutes until they are all evenly red.
3. Coat with Tapioca Starch: Add the water chestnuts to the tapioca starch and mix until they are coated well. Strain them with a mesh sieve or colander to get rid of the excess flour. If you prefer a more gummy texture, add another layer of tapioca starch by misting them with water and coating them with the starch again.
4. Cook the Red Rubies: Place the coated water chestnuts in a pot of boiling water and cook for approximately one minute. Once they float to the surface, they are done. Remove and plunge into a pot of ice cold water. Once in the ice water, they'll transform into shiny, clear red rubies. If you notice spots of white (uncooked tapioca starch), put them back into the boiling water to cook for a minute longer.
5. Make the Coconut Syrup: Make a simple syrup by heating equal parts water with white granulated sugar. If you like, you can add a bruised and knotted pandan leaf to the syrup mixture while it cooks to infuse the syrup with pandan flavor. Once it cools, add the coconut milk and stir together.
6. Serve over Crushed Ice: Allow the coconut syrup to cool to room temperature. Add crushed ice and the prepared red rubies. Stir and enjoy immediately!

Storage

The red rubies tend to stick to each other if they are not submerged in a liquid. You can store them in a little simple syrup to help keep them separate.

They can be kept at room temperature for several hours, but after that, they'll need to be refrigerated. Be warned - they will harden in the fridge, so it's really best to make them within a few hours of serving this dessert. The coconut syrup, however, can be made days in advance and kept in the fridge with no problems.

Red Rubies Dessert FAQs

Pairs Well With...

This Thai Red Rubies Dessert is wonderful on a hot, summer day. It'd be a great end to a backyard meal with your favorite Thai grilled foods, or just as wonderful as a refreshing mid-day snack. The chewy, crunchy red rubies with sweet, cold coconut milk is just so delicious whenever you serve it!