First grind ginger , coriander and green chiilies to a paste.
Heat oil in a cooker , add mustard seeds and then the chopped cabbage and potato.
fry for 5 mins in low flame .
then add the grinded masala and salt.
Keep the cooker for one whistle and put off the flame.
After a few mins , open the cooker , mash the potatoes and serve hot with roti or chapatti.