Remove the spinach leaves from the stem.
Wash the leaves very well.
Roughly chop the leaves.
Peel potatoes, cut into desired size of pieces and keep them inside water until used, otherwise they tend to turn brown.
Heat oil in a pan and add Asafoetida and cumin seeds. Let seeds splutter.
Add ginger garlic paste and green chillies. Saute on low heat until ginger garlic paste turns brown.
Add onion and cook until it turns slightly brown.
Then add tomato puree and mix well.
Put a lid on and let puree cook on low heat, with occasional stirring until tomatoes begin to leave the sides of the pan. It will take about 10 to 12 minutes.
Add red chilli powder, turmeric powder and coriander powder. Mix.
Then add potatoes, water and salt. Mix.
Put a lid and let potatoes turn slightly soft for 5 minutes.
Uncover and add spinach. Mix and let it cook covered with occasional stirring.
In 10 to 15 minutes, spinach and potatoes will be cooked properly and water is going to dry out. You can check so by pressing a piece of potato.
Lastly add garam masala and mix well. Saag aloo is ready. Serve hot with roti, naan or anyway you like.