Combine the pandan leaves and 400 ml water in a blender. Blend on high for 1 minute until fully broken down and bright green.

Strain through a fine-mesh strainer into a bowl, pressing on the solids to squeeze out all the liquid. You should have about 350 ml of pandan juice, top up with water if you're short.

In a 2-quart / 2L saucepan, whisk the rice flour, tapioca starch and 1/4 tsp salt with the pandan juice until smooth with no lumps.

Set the pan over medium heat and cook, stirring constantly with a spatula, for 8 to 10 minutes. The dough turns from thin and cloudy to thick, glossy, and translucent green, pulling away from the sides of the pan. Don't stop early, an undercooked dough falls apart the moment it hits the ice water.

While the dough cooks, fill a large bowl with the cold water and ice cubes and set it next to the stove.

Working quickly while the dough is still hot, spoon it into a lod chong press or a colander with 5-6 mm holes held over the ice water. Press the dough through with a spatula so it drops into the water in short noodle strands.

Let the noodles sit in the ice water for 2 to 3 minutes until firm, then drain in a colander. Repeat with any remaining dough.

In a 1.5-quart / 1.4L saucepan, combine the coconut milk, palm sugar, granulated sugar, the remaining 1/4 tsp salt, and the knotted pandan leaves.

Warm over medium-low heat, stirring occasionally, for 4 to 5 minutes until the sugars dissolve. Keep it below a hard boil, high heat can split the coconut milk and turn the sauce grainy. Remove from heat and discard the pandan leaves.

Divide the drained noodles among 6 serving bowls or glasses.

Ladle the coconut sauce over the noodles and top each bowl with a handful of crushed ice. Serve right away.