Pressure cook the soaked drained chana with 1 1/2 cups water until soft - it took me three whistles and 6-7 minutes on sim. Since these chana varieties have a thick skin, they don't easily turn to a mush, so nothing to worry here. When the cooker has cooled off, drain chana and keep aside.
In a wok, heat 1 tsp oil. Add the asafoetida, cumin and mustard seeds. Once they splutter, add the onions and cabbage with a pinch of salt, stir for 2 minutes on medium flame till slightly soft. Remove from the wok and cool.
In a large bowl, combine all ingredients for dressing. Whisk well. Add the boiled drained chana, the cabbage-onion mix and toss to coat evenly.
Garnish with shredded cabbage and serve chilled with papad or baked chip.