I got the recipe for the powder from one of Chef Venkatesh Bhat's "Samayal Samayal" episodes. Jotted it down quickly as I watched, so hope I got it right.
It's important to toast the spices only in coconut oil. That is what makes it udupi cuisine. I also used a tsp of fresh coconut and fried it along with the spices. Totally my variation, optional.
It's also important to add the jaggery at the end to balance out the sourness. I initially didnt buy into the idea, but loved it once I tried making it. Of course, when you make it yourself, you can control how much jaggery you add. I add just a tiny bit.
The powder can be stored for a week or two, and used as a finishing podi for curries such as tindora (ivy gourd), and eggplant.