Udupi cuisine extensively uses coconut in almost every other dish. In fact, some sambars hardly use any toor dal, but are made with just ground coconut and sambar masala. A 'boLu huLi' neither requires coconut, nor requires sambar powder. The use of tamarind differentiates this huli from a regular tovve(dal).
Green chili, gives this huli a distinctive taste. Of course, you need to add a lot of them to compensate for the lack of sambar masala.