Make the ginger-garlic paste - put equal amounts of peeled and chopped ginger and garlic along with a few tablespoons of water in a blender and blend to a smooth puree. Skip this step if using store-bought paste.
Instant Pot Method
Turn the instant pot to saute mode (normal) and add cumin. When it splutters, add onion and saute until it turns reddish-brown.
Add the ginger-garlic paste, tomato, salt and powdered spices. Saute for 5 minutes, adding splashes of water to keep the masala from sticking to the bottom of the pot.
Add the mince and saute for 10 minutes. Add ½ cup water and cancel the saute mode.
Turn on the pressure cooking mode, secure the lid, make sure the vent is in sealing position and set the timer to 5 minutes.
Do a QPR (Quick Pressure Release) after 10 minutes and open the cooker.
Add the cubed potatoes and again pressure cook for 1 minute with QPR.
Open the cooker and garnish with cilantro, green chillies and slivered ginger. Serve warm with Indian bread or steamed rice.
Stove-top Method
Heat the oil in a pan and put the cumin seeds in it.
Add the sliced onions and cook until they turn brownish-red.
Stir in the ginger-garlic paste and saute for a minute or two.
Add the tomatoes, salt and powdered spices and sauté for 5 minutes, Add splashes of water to prevent the masala from sticking to the pan, and cook until it becomes a thick, shiny paste. (approx. 10 minutes).
Add the mince and mix it together with the masala. Sauté for 10 minutes on medium heat.
Add one cup of water, cover and simmer for 15-20 minutes. Stir a few times in between.
Take off the lid and add the potatoes. Add more water if necessary. Cook for another 10-12 minutes. When all the water has evaporated, keema aloo is done.
Notes
If you don’t have ginger-garlic paste or don't want to make it, just chop the stuff (1 tablespoon finely chopped garlic and 1 tablespoon finely chopped ginger). Chopped ginger-garlic tastes just as good.
For even better tasting mince, add a small, finely chopped onion (omelette style) along with the potatoes. The onion will turn translucent very quickly and look and taste great.