Soak the navy beans in 5 cups of water in a covered jar for 18 hours.

Finely dice the salted pork fatback, discarding the skin.

Dice the onion.

Place the diced fatback in a pressure cooker (lid off) over medium heat and cook until it starts to sizzle.

Drain the beans, reserving the water.

In a small bowl, mix together the molasses, ketchup, mustard, and savory, adding a little bean water to make it pourable.

When the fatback sizzles, stir it and add the drained beans.

Add the diced onion, about half of the reserved bean water, and the condiment mixture. Stir well.

Add more bean water until it just covers the beans, using it to rinse any remaining condiments from the bowl.

Seal the pressure cooker with the high-pressure valve.

Bring to high heat until steam comes out, then reduce the heat to the lowest setting that maintains a whistling sound.

Cook for 40 minutes, then remove the cooker from the heat and wait at least 20 minutes before opening.

If there is excess liquid after cooking, stir the beans, reseal the lid, bring to high heat until it whistles, then remove from the heat and wait 10 minutes before opening.