Place 3 large potatoes in a pot and cover with salted water.
Bring to a boil, then reduce heat to medium-low and cover.
Simmer until potatoes are tender, about 20 minutes, then drain.
Allow potatoes to steam dry for a minute or two.
Remove and discard potato skins, then mash the potatoes into coarse chunks.
Heat 2 tablespoons of cooking oil in a skillet.
Fry 2 red chile peppers, 1 teaspoon skinned split black, 1 teaspoon cumin seeds, and 1 teaspoon mustard seeds in the hot oil until the seeds begin to splutter.
Add 2 sliced onions, 3 chopped green chile peppers, 1 sprig of curry leaves, and 1/4 teaspoon asafoetida powder to the skillet.
Continue cooking until the onions soften but not yet beginning to brown.
Stir the mashed potatoes and 1 cup of water into the skillet mixture.
Season with salt to taste, then increase heat to high and bring the mixture to a boil.
Cook at a boil for 5 minutes.
In a small bowl, mix 1 tablespoon chickpea flour and 1 tablespoon water to make a paste.
Add the paste to the skillet and stir.
Continue cooking and stirring until the mixture thickens, about 2 to 3 minutes.