In a mixer grinder grind together onions, cumin seeds and red chillies until it is smooth.
Remove skin of yam and slice it into 1" cubes.
Heat oil in a tawa and add the yam cubes.
Sauté for a minute or two.
Add the ground masala and add turmeric powder and salt.
Cover and cook until the yam pieces are cooked and soft.
Now remove lid and keep on cooking until all the water content is evaporated.
Add more oil if needed.
Keep on stirring at regular intervals on low to medium flame until the yam pieces starts turning crisp.
Once all the yam pieces are nicely roasted and have changed colour, remove from flame and serve them hot as a side dish to rice.
