To your food processor/blender add the spinach leaves along with little water to make a puree. Puree spinach along with water. Set aside.
Next puree tomatoes with ginger and green chili. Set aside.
Press saute mode on IP and add oil. Once the oil is hot, add cumin seeds and let it crackle.
Add copped garlic, saute till it starts turning golden in color.
Then add chopped onions, saute for 2 minutes till it starts changing color.
Add the pureed tomatoes, stir, cover the pot slightly and cook for 3 minutes.
Remove cover, add salt, coriander powder, garam masala, turmeric powder and cumin powder. Stir, cover and cook for another 2 mins.
Add pureed spinach and stir.
Cover and cook for 2 more minutes. This is how I covered the IP, don't seal it just keep the cover on top of the pot.
Remove cover and add cubed potatoes and stir.
At this point add water if you want a more watery curry. I added little water here.
Cancel saute mode. Press manual more and select high pressure for 6-8 minutes. 8 minutes will result in overcooked potatoes, if you want your potatoes to be bit firm, go for 6 minutes. Vent should be in sealing position.
Once pressure comes off, open the pot and give a stir.
Add fresh lemon or lime juice.
Serve aloo saag with rice or any bread of your choice. It tastes great with boiled rice.