1. You can add any vegetables/greens you have on hand in place of the butternut squash here and simmer until done, that's what makes this stew so versatile.
2. Curry leaves are completely optional here, but if you can get your hands on some, add them - their unique flavor works very well in this stew.
3. Traditional sambar calls for
hing and
tamarind. If you have one or both, add ⅛ teaspoon of hing to the pan with the toasting spices, towards the end and add to the stew with the rest of the toasted spices and ghee/oil. Add 2 teaspoons tamarind paste in place of the lemon/lime juice and simmer stew for another 5 minutes to let the flavor incorporate.