It took me a lot longer than I originally thought it would to get around to making this dish. I was amazed at how well the curry leaves held up in the fridge!
(Apologies for the dark photos.

)
Most of the Mis en Place for the Rice:

I cooked some basmati rice in my rice cooker. The rest of the preparation consisted of three separate processes. First - soak the tamarind pulp in hot water and then push the water and pulp through a chinois. Bring it to a boil with the rasam powder, some salt, and brown sugar. Simmer until thickened. Next - in a dry skillet, toast the cumin seeds, fenugreek seeds, black peppercorns, and sesame seeds. Let cool and grind in a spice grinder. Add that mix along with a couple of tablespoons of unsweetened coconut to the tamarind liquid and keep warm. Lastly - toast some peanuts in ghee, remove, and then add the curry leaves and black mustard seeds to the remaining ghee and toast until the seeds pop.
When the rice is done, mix in the tamarind liquid, the peanuts, and the ghee mixture.
Doesn't look like much, but this was very tasty:

(Edited to add, my source for what I describe generally above is "Great Vegetarian Dishes: Over 240 Recipes From Around the World" by Kurma dasa. The complete recipe is on page 11.)
I served it with some Tandoori-Style Fish:

Thanks, everyone, for all the tips! I did freeze the leftover tamarind.