Another classic Andhra preparation. This dish goes perfectly with Aaku Pappu. I even like it as an accompaniment to khichdi. This tastes best with homemade buttermilk, but you can use commercial buttermilk too.
Stir the buttermilk, turmeric, and salt together in a bowl. Add the curry leaves and green chiles, but do not stir into the mixture.
Heat the vegetable oil in a small skillet; add the chile peppers, fenugreek seeds, mustard seeds, cumin seeds, and asafoetida powder to the oil. Fry the mixture until the seeds splutter. Pour the mixture over the curry leaves and green chiles. This will quickly fry them and release a nice aroma. Serve cold or at room temperature.