Pour boiling water atop the chili and set aside to hydrate for 15 minutes. Drain, reserving liquid, and coarsely chop the chili.
Combine cilantro, salt, garlic, and chili in a small blender jar, food processor, or mortar and pestle. Mix to a colorful paste. You could also do this step by finely chopping the blend on a cutting board.
Heat oil in a medium skillet over medium heat; add the cilantro/chile/ garlic paste. Stir-fry for 1โ2 minutes.
Add the potatoes and turmeric, and stir-fry about 1 minute. Pour in the reserved chili water and heat to boiling. Reduce heat and simmer, covered, stirring occasionally for 15โ20 minutes, until potatoes are tender.
Combine buttermilk and cream. After potatoes are tender, stir in buttermilk/cream mixture and heat 2โ3 minutes to warm.
Serves 4 atop rice or with bread to soak up the delicious sauce.