Rinse the urad dal thoroughly under running water, then soak it in enough water to cover it fully until the grains turn soft and swell up.

Drain the soaked urad dal and grind it in a wet grinder, adding chilled water a little at a time, until it forms a thick, smooth batter.

Whip the ground batter vigorously by hand in one direction until it turns noticeably lighter, fluffier, and increases in volume.

Gently fold the chopped onion, green chili, ginger, curry leaves, crushed black pepper, cumin seeds, and salt into the whipped batter, mixing just enough to combine without deflating it.

Let the seasoned batter sit for a short while so the flavors settle and the texture firms up slightly, making it easier to shape.

Pour the oil into a kadai and heat it over medium-high heat until a small ball of batter dropped in rises to the surface steadily within a few seconds.

Wet your palms, take a portion of batter, flatten it into a disc, punch a hole through the center with your thumb, and carefully slide it into the hot oil.

Fry the vadas without disturbing them until the undersides turn golden brown and firm enough to flip without breaking.

Flip each vada with a slotted spoon and continue frying, turning occasionally, until they are evenly deep golden brown and crisp on all sides.

Lift the vadas out with the slotted spoon and place them on a plate lined with paper towels to drain off excess oil before serving.