Olan is one of the simplest and tastiest dishes I have ever come across, just green chillies and coconut oil to flavor the whole dish. My mom would make it using coconut milk, but I like it just plain and without the richness of the coconut milk. When I use to cut the pumpkin for my mom she would always remind me to cut them into flat squares and not cubes. She had all these rules about how each vegetable should be cut for each dish, and these rules I think are followed by most Keralites. Because when I got married my husband and his family had the same vegetable cutting rules. I usually serve this with something sour like rasam or tomato dal , just to offset the blandness and balance the meal. Indian meals are all about balancing different flavors.