Put the tapioca flour in a bowl, pour the boiling water over and stir with a pair of chopsticks to mix it all through.
When the mixture is cool enough to handle, knead in the bowl for 1-2 minutes, to form a soft dough.
Divide the dough into three equal portions. Keep one portion as a white dough; add 1-2 drops of red food coloring to the second portion and knead to make a pink dough; add 1 drop of green food coloring to the third portion and knead to make a green dough.
Tear off a small piece of dough (about 3 grams, 1/8 ounce) and roll it into an oval shape.
Using your thumb, firmly press the dough onto a gnocchi board or sushi mat, then smear and roll forward to create ridges so it looks like a little cocoon. Repeat with the remaining white, pink and green dough.
Bring a large saucepan of water to a rolling boil over high heat.
Add the dumplings, stirring occasionally to stop them sticking to the bottom of the pan.
When the water comes back to a boil, reduce the heat to medium and simmer for 5 minutes, or until the dumplings are slightly transparent.
Remove with a wire strainer and transfer to a bowl of iced cold water to cool to room temperature.
Place all the coconut syrup ingredients (coconut milk, water, caster sugar, and salt) in a saucepan and bring to a simmer over medium-low heat.
Stir until the sugar has dissolved, then add all the drained dumplings to the syrup and cook for 2 minutes.
Remove from the heat and cool to room temperature.
Serve the dumplings in individual serving bowls, drizzled with the coconut syrup and garnished with sesame seeds.