Wash Arbi, boil or cook it into a pressure cooker with required water and salt for 2-3 whistle.
Once cool down, peel the Arbi roots and cut it into big cubes.
Heat oil in a kadhai for deep frying. Fry Arbi cubes till golden and crispy outside, remove it on absorbent paper and keep aside.
Heat 2 tbsp oil in another kadhai. Add cumin seeds, mustard seeds, big cardamom and pinch of hing.
Add chopped green chili, garlic, chopped onion and saut it till golden brown.
Now add grated ginger, tomato puree and again saut it for two minutes. Add red chili powder, turmeric powder, garam masala and fry or saut it till oil separated.
Add yogurt, stir it continuously, mix it well and stir it till boiling point. Add ¼ cup water and boil the gravy again with continue stirring.
Now add fried Arbi cubes, salt, kasuri methi and mix it well, cover it and cook it for 3-4 minutes on medium to low flame.
Dum Arbi is ready now, garnish it with chopped coriander leaves. You could server with any Indian flat bread.