Soak the chickpeas overnight.
Sieve the soaked chickpeas to remove the water and put them into the pressure cooker.
Peel, slice and dice the white onion.
Heat 2 cups (1 litre) of water in the water boiler. Poor the boiling water into the pressure cooker and let the chickpeas boil for 5 minutes. You will notice a layer of foam forming along the top of the water. Sieve the chickpeas to remove the water and wash them with tap water to make sure the foam is removed.
Put the chickpeas back into the pressure cooker and start heating 4 cups (2 litres) of water in the water boiler.
Add the onions, garlic powder, salt and pepper in the pressure cooker and mix with the chickpeas.
Add the boiling water in the pressure cooker and mix.
Turn the heat on (high heat) and close the lid. Turn the pressure-limiting valve to "I" (for low pressure).
Wait until the safety open-preventing valve raises and reduce the heat to very low.
After 50 minutes, turn the heat off and remove the pressure cooker from the stove. Open the lid when the safety open-preventing valve falls down.
Add the olive oil and lemon juice, mix and let the food stand for 5 minutes. You are ready to serve!
Add the feta cheese on top, if you want to (30g per portion)!