Red Rubies Dessert (Tub Tim Krob)

Tub Tim Krob (ทับทิมกรอบ) is a traditional Thai dessert made with crunchy water chestnuts coated in chewy tapioca flour. The little red rubies are served with a sweet pandan coconut sauce and crushed ice.

Tub Tim Krob is delicious on its own, but it's also one of the colorful toppings I use in my Ruam Mit Thai mixed dessert and Nam Khaeng Sai (Thai Shaved Ice).

Red is traditional, but you can make other colors too. My daughter and I have made different little “gemstones” using butterfly pea, pandan, and ube coloring.

Jump to:

• What Is Tub Tim Krob?
• Ingredients
• How to Make Tub Tim Krob
• Suwanee's Tips
• Serving and Storing
• More Thai Desserts
• Red Rubies Dessert (Tub Tim Krob)
• More Authentic Thai Desserts You'll Love

What Is Tub Tim Krob?

Tub Tim Krob means "crispy rubies." Diced water chestnuts are colored red, coated in tapioca flour, and boiled until the outside becomes translucent and chewy.

The finished pieces look like little red pomegranate seeds or rubies, which is where the dessert gets its name. 

You may also see it spelled Tub Tim Grob, Tab Tim Krob, or Thap Thim Krop.

Ingredients

• Water Chestnuts. Fresh or canned water chestnuts work. I usually use canned because they're easy to find. Dice them into small cubes, about ¼ inch. You can make them a little larger or smaller depending on how much crunch you like.
• Tapioca Flour. Tapioca flour creates the soft, chewy coating around the crunchy water chestnuts. Coat them generously, then shake off the excess flour before cooking.
• Red Food Coloring. Red is the traditional color and gives Tub Tim Krob its ruby-like appearance. You can make other colors too. My daughter and I have made different "gemstones" using butterfly pea for blue, pandan for green, and ube coloring for purple.
• Coconut Cream. Coconut cream makes the sauce rich and creamy. I gently heat it with sugar, salt, and pandan leaves until everything dissolves. If using coconut milk instead, choose a good full-fat coconut milk. You can read more in my Thai coconut milk guide.
• Pandan Leaves. Pandan adds a light fragrance to the coconut sauce. Fresh or frozen leaves both work. Read more about pandan leaves and how I use them in Thai cooking.
• Sugar and Salt. Sugar sweetens the coconut sauce while a little salt balances the richness. I use white sugar to keep the sauce light in color, but palm sugar can also be used for a deeper flavor.
• Water. A small amount is used to mix with the food coloring, and 3-4 cups are used for boiling. You'll need enough water to cook the water chestnuts. 

How to Make Tub Tim Krob

1. Prepare the Water Chestnuts. Drain and rinse the water chestnuts. Dice into small cubes, about ¼ inch. If you're using canned water chestnuts, I like to soak them in cold water for a few minutes and drain well before using.

2. Add the Color. Mix the red food coloring with a little water and toss with the diced water chestnuts until evenly coated. Let them sit for about 5 minutes, then drain off any excess liquid.
3. Coat with Tapioca Flour. Add the colored water chestnuts to the tapioca flour and toss until each piece is well coated. Transfer them to a fine-mesh strainer and shake off the excess flour.

4. Cook the Rubies. Bring a pot of water to a rolling boil. Add the coated water chestnuts. They will sink at first. Cook until they float to the top and the tapioca coating becomes translucent. Transfer immediately to an ice-water bath and let cool. Drain well, then toss the cooked rubies with a small amount of the syrup to help keep them from sticking together.

5. Make the Coconut Sauce. Add the coconut cream, sugar, salt, and pandan leaves to a small saucepan. Warm gently over medium-low heat, stirring until the sugar and salt dissolve. Don't let the coconut sauce come to a hard boil. Remove from the heat and let cool. Remove the pandan leaves before serving.

6. Serve. Spoon the Tub Tim Krob into small dessert bowls and add the sweet pandan coconut sauce. Top with crushed ice and serve right away. You can also add sliced jackfruit or young coconut meat if you like.

Suwanee's Tips

• Cut the chestnuts to your liking. I like mine around ¼ inch, but smaller pieces give you a more delicate crunch while larger pieces give you more water chestnut in each bite.
• Shake off the extra tapioca flour. Too much loose flour can make the cooking water thick and cloudy.
• Watch for them to float. Once the rubies float and the coating looks translucent, they're ready to come out.
• Use an ice bath. Transfer them directly from the boiling water into ice water to stop the cooking and cool them quickly.
• Don't make them too far ahead. Tub Tim Krob has the best texture when freshly made.

Serving and Storing

• Tub Tim Krob is especially good cold with crushed ice. You can serve it simply with the coconut sauce or add jackfruit or young coconut.
• It's best eaten the day it's made. The tapioca coating will change texture as it sits, especially once mixed with the coconut sauce.
• If you're preparing the dessert ahead, keep the coconut sauce and cooked rubies separate and assemble shortly before serving.

More Thai Desserts

• Pandan custard
• Nam Khaeng Sai, Thai shaved ice
• Bua Loy
• Mango Sticky Rice
• Thai Coconut Ice Cream

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