In a large pan or wok over medium heat, heat the oil. Add the cumin seeds and fry for a few seconds until they sizzle.
Add the chopped onion, garlic, ginger paste, and green chillies. Cook for 5-7 minutes until the onions turn translucent and the mixture is fragrant.
Add the diced potatoes to the pan and stir well to coat them with the onion mixture. Fry for 5 minutes, stirring occasionally.
Mix in the coriander powder, turmeric powder, garam masala, chilli powder, and salt to taste. Cook for 2-3 minutes.
Stir in the chopped fenugreek leaves and spinach. Cook for 15-20 minutes or until the potatoes are cooked through.
Serve hot with naan bread or rice.