Crunchy and refreshing water chestnuts pieces are wrapped in soft and chewy tapioca dough, resembling red ruby gems. The dessert is served in rich and creamy coconut milk.
I used canned water chestnuts that have been peeled. Dice them into 1/2-inch pieces. Get two large bowls, one for red and one for blue rubies
If using natural coloring, mix the red yeast rice powder with hot water and stir to dissolve. Strain the mixture and then add 100 grams of the water chestnuts and let them soak for at least 15 minutes
Soak the blue pea flowers in hot water for 15 minutes. Discard the flowers and collect the blue liquid. Soak the rest of the water chestnuts for at least 15 minutes
If using food coloring, put 2 Tbsp of water and 1-2 drops of red food coloring in the bowl. Add the water chestnuts pieces into the red and another 100 gr of water chestnut into the blue food coloring. Let them soak while you prepare other things
Prepare coconut milk sauce:
Put all ingredients in a saucepan and let it simmer gently for about 5 minutes. Don't let it boil over. Remove from the heat and keep it chilled in the fridge until ready to serve
Coat chestnuts with tapioca flour:
Bring a large pot of water to a boil. Drain off the red and blue liquid. Sprinkle the first 1/3 cup of tapioca flour on the red rubies and another 1/3 cup of tapioca flour on the blue ones. Toss them to coat with flour
Then add a second 1/3 cup of tapioca flour on the red rubies and another 1/3 cup of tapioca flour on the blue ones. Toss them lightly to coat. Use a sieve to shake off excess flour. The rubies should be fully coated and white in color
Boil the rubies:
Put the rubies in the boiling water and stir to prevent the rubies from sticking to each other at the beginning. Let the water comes back to a boil and when the rubies float to the top, let them cook for another 2 minutes or so
Check for doneness:
The cooked rubies should be transparent. If you see lots of white specks, the rubies are not cooked through yet, let them cook for few more minutes
Soak in ice water:
Remove from the boiling water using a sieve and immediately transfer to a bowl of ice-cold water to stop the cooking process
To serve:
Portion out the red and blue rubbies and then ladle the chilled coconut milk sauce over. Add more ice cubes if you like and serve immediately