Soak the rice and dal in a large bowl with plenty of water for 10 to 12 hours at room temperature.

Drain the soaked rice and dal, then transfer them to a blender with water. Blend until mostly smooth but still slightly textured, similar to wet sand. Add a splash more water if the blades stall.

Transfer the batter to a large bowl, cover, and place in a warm spot—like an oven with the light turned on—to ferment for 10 to 12 hours. The batter should look slightly aerated and smell faintly tangy. Stir the salt into the fermented batter.

Set up a steamer by placing a rack or ramekin inside a large pot filled with a few inches of water. Ensure the water level is below the rack, bring it to a boil, then reduce the heat to a simmer and cover.

Grease an 8-inch round cake pan or steaming pan with oil or cooking spray. In a separate bowl, scoop out roughly one-fourth of the batter and whisk in a little water until it reaches the consistency of a pourable cake batter.

Add a portion of the fruit salt to this batch of batter and sprinkle a teaspoon of water directly onto the powder to activate it. Whisk vigorously until the batter looks foamy, then immediately pour it into the prepared pan.

Sprinkle the top with black pepper and ground red chili. Place the pan into the steamer, cover tightly, and steam for 12 to 15 minutes, until a toothpick inserted into the center comes out clean.

Remove the pan and immediately brush the surface with a thin layer of oil to keep the cake moist. Let it rest for 5 minutes before cutting into 2-inch diamonds. Repeat the process in batches with the remaining batter. Serve warm or at room temperature.