Heat oil in a pan. add mustard seeds, when they start to splatter add asafoetida powder, split black gram, green chili and curry leaves. sauté until the black gram turns golden brown.
Now add the cabbage, sprinkle water. Cover and cook in low flame. Time to time stir, sprinkle water in between to prevent from getting burnt. Add salt as needed. NOTE: keep in mind cabbage release water as well.
Once the cabbage is cooked (becomes translucent), add coconut mix well and serve.
You can steam cook the cabbage and do this as well.