Place the rice flour, sugar, salt, and yeast in a large bowl and mix well.
Add water a little at a time and mix well until you have a smooth batter without any lumps.
Leave the batter to sit in a warm place for 4 to 6 hours. The time needed for fermentation can be different according to the room temperature; the key is to use your intuition.
After fermentation, the batter should be thick and smell fermented. Gently stir the batter. (An hour before you intend to cook and serve the hoppers)
Thin the batter adding coconut milk a little at a time. Dissolve the baking soda in a tablespoon of warm water. Add to the batter and mix well.
Cover and leave in a warm place for about 30 minutes to one hour. After resting time, the batter is full of tiny air bubbles.
Gently mix the batter. Season with salt to taste.
Heat the pan over medium-high heat until it becomes hot.
Pour a ladleful of the batter into the center of the pan. You will hear the sizzling sound when the batter hits the pan if it’s hot enough.
Tilt the pan to spread the batter thinly.
A thin layer of batter should stick to the sides, with a thicker layer in the center.
Cover and cook for about 2 minutes over medium heat until the edges of the pancake are starting to brown, and the center is no longer runny.
Run around the edges with a palette knife and ease it onto a plate.
Best served hot.