Prepare the buttermilk: Whisk the buttermilk until smooth. If using curd, whisk it with water until it reaches a thin, pourable consistency.
Make the jhol mixture: In a small bowl, combine the besan, turmeric powder, salt, chopped green chillies, and cumin seeds. Gradually whisk this mixture into the buttermilk until smooth and free of lumps.
Cook the jhol: Pour the mixture into a heavy-bottomed steel or copper pan and place it over medium heat. Stir continuously to prevent the besan from settling at the bottom. As the mixture heats, it will become smooth, develop a gentle yellow colour, and thicken slightly while retaining its light, soupy consistency. Once it reaches a gentle boil, continue cooking for another 3–5 minutes. Avoid a vigorous boil, as it may cause the buttermilk to split.
Prepare the tempering (optional): Heat the ghee or mustard oil in a small tempering pan. Add the cumin seeds and asafoetida, if using. When the seeds begin to crackle, pour the tempering over the hot jhol and stir gently. Garnish with freshly chopped coriander leaves.
Serve: Serve Mandyali Buttermilk Jhol hot over steamed rice. In a traditional Mandyali Dham, it is served as the final course, bringing the meal to a simple and refreshing close.