(rather than a paste of onions and tomatoes?)
A can of coconut milk.
Add more water, mash some chickpeas and mix well to thicken the sauce. Don't forget to adjust your seasoning. If you are making chhole, then coconut milk is generally not used. But there's nothing to stop you from making it your own either!
Coconut milk isn't really used in dal either, but Vikram Vij uses it in his and it's the best I've ever had.
If you soak your chickpeas and boil them separately, try adding some of the cooking liquor to the mix. That should add some extra flavor and mass to the party.
I just looked at three different chickpea recipes in an Indian cookbook I have:
the chana masala calls for 2/3 c. vegetable oil plus 2 T. plain yogurt,
the "sweet and sour" chickpeas calls for 1 T. ghee and two chopped tomatoes, and
the chole chaat calls for 2 T. oil and diced tomatoes.
The above are per every cup dried chickpeas.
@Soft Punk, I come from the western coastal region of India where we add ground coconut and/or coconut milk to dals and greens to make what we call patal bhaji. :-)
Ooh, ground coconut. That sounds delicious!