If you ask which is the best combo of vegetables for making kara kuzhambu means I would say its brinjal and drumstick. Both the veggies goes well with even sambar and same applies for kara kuzhambu too. I make this basic kuzhambu and make with other veggies like ladies finger and even Parupurundai kuzhambu. I love it a lot and this tastes great with rice,sesame oil/ ghee or even tastes good with dosa. I make usually the no-coconut kuzhambu like this, but make this occasionally when I have coconut in stock.
Serve with rice and any curry, kootu or poriyal. I had with vazhakkai curry.