In a large bowl, combine the whole wheat flour, chopped onion, minced green chilies, grated ginger, chopped curry leaves, chopped coriander leaves, cumin seeds, asafoetida (if using), and salt.

Gradually add 1.5 to 2 cups of water while whisking continuously to create a smooth, pourable batter; it should resemble buttermilk.

Cover the batter and let it rest for 15-20 minutes to allow the flour to hydrate fully, which improves the dosa's texture.

Heat a non-stick griddle or cast-iron tava over medium-high heat, then reduce the heat to medium.

Lightly grease the griddle, then pour a ladleful of batter onto the center and quickly spread it outwards in a circular motion to form a thin, even dosa.

Drizzle oil or ghee around the edges and over the top, cooking for 1-2 minutes until the edges are golden brown and lift; then flip and cook for another 30 seconds to a minute until lightly browned.

Remove the cooked dosa and repeat with the remaining batter, serving all dosas hot.