Rinse the urad dal thoroughly and soak in ample water for 4‑5 hours or overnight. Use a wide bowl to allow the dal to expand.

Drain the soaked dal, transfer to a wet stone grinder, and blend on medium speed with just enough water (≈80 ml) to form a smooth, glossy batter. The batter should be thick enough to hold its shape when dropped from a spoon.

Transfer the batter to a large mixing bowl. Add salt, crushed peppercorns, cumin seeds, asafoetida, grated ginger, chopped green chilies, torn curry leaves, and finely chopped onion. Mix gently with a spatula on low flame for 1 minute to incorporate, ensuring the batter stays airy.

Cover the bowl with a clean kitchen cloth and let it ferment in a warm spot (30‑35 °C) for 6‑8 hours or until the batter rises slightly and shows tiny bubbles. If using baking soda, stir it in just before frying.

Place a deep, heavy‑bottomed kadai (wok) on medium‑high flame. Add enough oil to submerge the vadas (≈3‑4 inches deep). Heat until a small drop of batter sizzles and rises to the surface within 5‑7 seconds – this is the ideal frying temperature (≈180 °C).

With a wet hand, scoop a tablespoon of batter, shape it into a doughnut by making a small hole in the centre, and gently slip it into the hot oil. Fry 2‑3 minutes on medium‑high flame until the vada turns golden‑brown and crisp, then flip and fry the other side for another 1‑2 minutes.

Using a slotted spoon, remove the vada, drain on paper towels, and immediately drizzle a few drops of warm oil over each to retain shine. Continue frying the remaining batter, maintaining the oil temperature; reduce flame to medium if the oil starts to smoke.

Turn off the flame. Let the fried vadas rest in the warm oil for 30 seconds; this final rest locks in moisture and ensures the interior stays fluffy.

Transfer the rested vadas to a serving platter, sprinkle a pinch of salt if desired, and garnish with fresh curry leaves for aroma.

Serve the Medu Vada hot, paired with coconut chutney and a side of sambar. For a traditional touch, accompany with a cup of strong South Indian filter coffee.

If preparing for a gathering, keep the vadas warm in a pre‑heated oven at 80 °C (Low heat) for up to 20 minutes without covering, to retain crispness.