Chop the onion. Heat the oil on medium heat and add the mustard seeds. When they pop, add the urad dal and curry leaves. Then add the onions and sauté till browned. Now add the cabbage, turmeric powder and salt. Stir for a while, lower the heat and cook covered for five minutes. Crush the garlic and cumin seeds and add to the cabbage along with the green chillies and the coconut. Stir for a few more minutes and remove from heat.