If you have soaked the beans already for a few hours, then you can skip right to the next step. If you have not, I would recommend rinsing the beans and adding to about 3 cups water along with an optional 1 tsp salt. Set aside until the rest is prepped.

While the beans soak, clean and mince the mushrooms and small red onion. Also crush or mince the garlic. Heat a stovetop pressure cooker on the stove to medium heat or turn your electric pressure cooker to sauté on medium. Add the mushrooms and onion and dry sauté for 2 minutes, stirring fairly frequently. If it gets stuck to the bottom, that’s ok, but try to scrape some off before it burns. You want some of the browned/burned bits, for their umami power, but you don't want anything fully burned.

Add the garlic and stir. Then add the drained beans and ½ cup water or vegetable stock (if beans soaked for hours already) or 1 cup water or vegetable stock (if the beans only briefly soaked).

Lock on the lid and bring to high pressure for 6 minutes (if beans were pre-soaked for hours) and up to 12 minutes (if beans were not pre-soaked for long). Allow pressure to release naturally. Test a few beans to make sure they are fully cooked. If not, re-pressurize for 2-3 minutes and allow pressure to release naturally. [While the beans cook, you can measure out and prepare all of the ingredients listed in the second step. Dry ingredients can be combined in one cup, and wet ingredients can be pre-combined in another cup. Set aside for later.]

Once beans are fully cooked, drain any remaining liquid and transfer to a medium bowl to cool. While the beans cool, clean out the pressure cooker pot and at least rinse the cooker top and silicon ring. (You will be reusing this to cook the sausages under pressure.)

Once beans are cooled (5-15 minutes), mash the beans with a fork, a potato masher or your hands. It shouldn't be like smooth, but you also want very few or no whole beans left.

While that sits, prepare your aluminum foil (and optional parchment paper) by cutting into squares that are about 5”x7” – but that’s a rough estimate. I’d say at least 3” by 6” is the minimum size, but you may want a larger square to make it manageable. I have used parchment before as an "inner" liner and I find it doesn't make much difference for the final result, so I skip that now. (I know some people dislike their food touching aluminum - I respect everyone has their own preference there. The science I've read says it doesn't matter, but who knows.)

Divide the mixture into 6 portions on top of the aluminum foil or parchment paper. Shape into rough sausage shapes and roll the wrapper around it, folding or twisting the ends to contain and hold the the sausage shape. The aluminum foil will help hold the shape in the pressure cooker, so use it as the outer wrapper if you used parchment paper as the inner liner. I don't have an exact strategy for the ends - twist or fold - but I think folding carefully probably provides the best shape.

Once you have them all shaped, add 1 cup water to the bottom of the pressure cooker and place the steamer basket or rack in the pressure cooker. Carefully place the wrapped “sausages” in the cooker, layering them on top of each other. I can usually place 3-4 on each layer, and then I switch the orientation for the next layer so they're alternating. I’ve never tried it another way, but this works for me.

Lock the lid on the pressure cooker and bring to pressure for 10 minutes. Allow pressure to release naturally. Remove the lid (carefully, as always) and let cool for a few seconds.

Carefully remove the sausages from the pressure cooker and unwrap gently. You may want to let them cool for another few minutes, so it's easier to unwrap them.

For the firmest sausages, refrigerate for at least 3 hours or overnight. I have refrigerated in the wrappers and out of the wrappers. Both methods work fine for me.

To heat and crisp the sausages, add them to a pan with a few tbsp of a neutral oil (less oil if you use a nonstick pan) and pan fry them over medium or medium-high for about 8-10 minutes total, with 2-3 minutes per side. Mine usually brown up quite a bit and develop a nice outer layer.

Serve with a great mustard, maybe over a nice slide of bread. Other suggestions for serving include sliced in a soup, or with baked beans, or in a hotdog bun or naan with traditional sausage fixings, like caramelized onions and relish.