Tub Tim Grob, often called “Red Rubies,” is a refreshing Thai dessert known for its jewel-like appearance and cooling taste. The dish features water chestnuts coated in vibrant red tapioca starch, giving them a chewy texture with a crisp bite inside. These ruby-like morsels are served in a sweet coconut milk base, often chilled with crushed ice, making it a popular treat in Thailand’s tropical climate. The name literally translates to “crispy rubies,” and it’s loved for its mix of textures, delicate coconut fragrance, and eye-catching presentation.
Preparation Time
30 minutes
Serving Size
Serves 4
Ingredients
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1 cup water chestnuts, diced into small cubes
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½ cup tapioca starch (plus extra for coating if needed)
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Red food coloring (natural beet juice or synthetic)
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1 cup coconut milk
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½ cup sugar (adjust to taste)
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½ teaspoon salt
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2 cups crushed ice
Detailed Recipe
Step 1: Prepare the Water Chestnuts
Place diced water chestnuts in a bowl. Add a few drops of red food coloring or beet juice and mix well until evenly coated. Let them sit for 10 minutes to absorb the color.
Step 2: Coat with Tapioca Starch
Drain any excess liquid from the water chestnuts. Toss them in tapioca starch until each piece is well coated. If the coating appears thin, lightly mist with water and toss again for a thicker layer. Shake off excess starch before cooking.
Step 3: Cook the Rubies
Bring a pot of water to a boil. Drop in the coated water chestnuts and stir gently to prevent sticking. When they float to the surface, cook for another 1–2 minutes. Use a slotted spoon to transfer them immediately into a bowl of ice water. This helps firm up the chewy texture.
Step 4: Prepare the Coconut Base
In a small saucepan, combine coconut milk, sugar, and salt. Heat over low flame until the sugar dissolves, stirring occasionally. Do not boil—this keeps the coconut milk smooth and prevents curdling. Let cool completely.
Step 5: Assemble and Serve
Drain the “rubies” from the ice water. Divide them among serving bowls. Pour chilled coconut milk over the top, add crushed ice, and serve immediately. The result is a sweet, creamy, and refreshing dessert with a delightful chewy crunch in every spoonful.
