Place potatoes in a large saucepan or pot.
Cover with water. Season with salt.
Bring the water to a boil, then reduce heat, and simmer for about 5-10 minutes or until easily pierced with a fork.
Drain potatoes, and allow to cool slightly.
Combine together yogurt, ground cumin, red chili powder, and lemon juice in a large bowl.
Add boiled potatoes, onion, and green chilies ( if using), and coriander (cilantro) leaves. Stir.
To temper spices, heat oil in a small frying pan over medium heat.
Add fenugreek seeds, and fry, for about 1 minute. Reduce heat to low.
Add ground turmeric and red chili powder. Stir. Remove from heat.
Add to salad. Stir.