Add the grated coconut, roasted chana dal, green chilies, sliced ginger, and salt to a blender jar along with 1/4 cup of water.
Pulse in short bursts, adding more water a little at a time, until the chutney is thick, creamy, and finely textured (resembling wet sand). Pour into a heatproof bowl.
Heat 1 tablespoon of coconut oil in a small tempering pan on medium heat until hot but not smoking.
Add the mustard seeds. Wait for them to begin popping and crackling vigorously to release their aromatics.
Add the split urad dal, dried red chili, curry leaves, and a pinch of asafoetida. Sauté for 15 seconds until the urad dal turns light golden and curry leaves crisp up.
Immediately pour the hot, sizzling tadka over the blended coconut paste. Gently fold the tempering into the chutney right before serving.