Making fluffy idli batter is a simple process if you follow these steps carefully:

1. Wash Rice and Dal: Rinse the rice and urad dal thoroughly under running water until the water runs clear. This helps remove excess starch.
2. Soak: In separate bowls, soak the rice and urad dal in enough water for at least 6–8 hours. You can soak fenugreek seeds with the urad dal to enhance fermentation.
3. Drain: After soaking, drain the water from both rice and dal.
4. Blend the Dal: In a blender, add the drained urad dal. Add a little water to help it blend until smooth and creamy.
5. Blend the Rice: Next, add the drained rice to the blender. Blend it into a coarse paste, adding water as required. The consistency should be slightly grainy.
6. Mix Both Pastes: Combine the rice and urad dal pastes in a large bowl. Mix well to ensure an even consistency.
7. Ferment: Cover the bowl with a lid or cloth and place it in a warm area to ferment. This might take 8-10 hours depending on the temperature. You will know it’s ready when the batter rises and shows bubbles on the surface.
8. Add Salt: Once fermented, gently fold in salt to taste. Avoid stirring too aggressively to retain the aeration in the batter.
9. Grease the Idli Molds: Lightly grease your idli steamer molds with oil or cooking spray to prevent sticking.
10. Fill and Steam: Pour the batter into the idli molds, filling each cavity about three-quarters full. Steam for about 10-15 minutes, or until a toothpick comes out clean.
11. Cool and Remove: Let the idlis cool for a minute before removing them from the molds. They should come out easily if they are greased well.