There's a recipe I want to try. It's from Maya Kaimal's "Savoring the Spice Coast of India," a Keralan book that I've otherwise had great luck with. She writes that it's traditionally made with kokum, a fruit (usually dried) that serves as a souring agent. Apparently assuming that we can't get kokum here, she doesn't call for it in this dish but substitutes 1 1/2 cups of chopped tomato (in a recipe that calls for 1 1/2 pounds of fish).
Maybe when the book came out a few years back, you couldn't get kokum in the States. Since then I've found it in New York and San Francisco (the only places I looked), and I'd like to give it a try. How many pieces should I use?