Sort through the Great Northern beans for broken, shriveled, or discolored beans. Rinse in a sieve under running water, and turn into a large bowl. Cover with cold water, plus one inch. Allow to soak for eight hours. Rinse and drain.
Alternatively, place the sorted and cleaned Great Northern beans in the pressure cooker and add water to cover, plus one inch. Bring to a boil, turn off the heat, and allow to soak for one hour. Rinse and drain.
Dice the onions.
Place the pressure cooker over high heat. When it is hot, pour in the olive oil, swirl it over the surface of the pan once, and immediately add the onions.
Reduce the heat to medium high and sauté the onions for 15 minutes, until translucent but not browned. Keeping the onions from browning will result in the best-looking finished dish, so if they begin to brown, reduce the heat to medium.
While the onions are cooking, mince the garlic. Depending on how much heat you prefer, mince the chiles (for more heat) or slit them lengthwise twice (for less).
When the onions are translucent, add the garlic and chilies and stir to combine. Cook for a minute or so, until the garlic is fragrant, but do not allow it to brown.
Add the bay leaves and salt. Pour in three cups of water and stir. Scrape down any matter above the water line on the inside walls of the pressure cooker.
Place the lid on the pressure cooker and secure it. Bring to pressure.
When pressure is reached, immediately begin timing eight minutes.
At the end of eight minutes, perform a quick release.
When the pressure has fallen and the cooker is unlocked, remove the lid.
Add the lemon juice. Check the salt and add 3 g (1/2 t) if desired.