Rinse the rice and split urad dal thoroughly, then soak separately in water for at least 4 hours or overnight.
Drain the soaked rice and lentils, then transfer them to a blender or grain grinder. Blend together with water until you achieve a smooth, pourable batter, about 2-3 minutes, adding a little water if necessary.
Pour the batter into a bowl, add salt, and mix well. Cover and ferment in a warm spot for 8-12 hours until it bubbles and slightlycreases in volume, with a tangy aroma.
Once fermented, stir the batter gently; it should be smooth and slightly thickened. If too thick, mix in a splash of water to loosen it slightly.
Heat a non-stick skillet or cast-iron pan over medium-high heat until hot and shimmering. Lightly brush with a little oil if needed.
Pour a ladleful of batter onto the center of the hot skillet. Using the back of the ladle, spread the batter outward in a thin circle, aiming for a crispy, even layer.
Cook the dosa until the edges turn golden and crisp, about 2-3 minutes. You should hear a gentle sizzle and see bubbles forming on the surface.
Carefully slide a spatula underneath and flip the dosa. Cook for an additional 1-2 minutes until the underside is crisp and deep golden brown.
Remove the crispy dosa from the skillet and place on a paper towel to absorb excess oil. Repeat with remaining batter, maintaining a hot skillet and adding oil as needed.
Serve the dosas hot, with your favorite chutneys or fillings, and enjoy their delicate crunch and savory aroma.
