Place the dried porcini mushrooms in a heat-safe bowl and cover with 1 cup of boiling water. Let them steep for 20 minutes until softened, then chop the mushrooms and reserve the soaking liquid, discarding any grit at the bottom.

In a large heavy-bottomed pot or Dutch oven, cook the chopped bacon over medium heat until crisp and the fat has rendered, about 5 to 7 minutes. Use a slotted spoon to transfer the bacon to a plate, leaving the fat in the pot.

Increase the heat to medium-high and add the cubed pork shoulder to the pot. Sear the pork until browned on all sides, about 8 to 10 minutes, then remove and set aside with the bacon.

Lower the heat to medium and add the diced onion to the pot, cooking until softened and translucent, about 5 minutes. Stir in the sliced smoked sausage and cook for another 3 to 4 minutes until lightly browned and fragrant.

Return the pork and bacon to the pot. Add the drained sauerkraut, shredded fresh cabbage, chopped mushrooms, reserved mushroom liquid, beef broth, tomato paste, caraway seeds, bay leaf, and black pepper. Stir well to combine all the ingredients.

Bring the stew to a gentle boil, then reduce the heat to low. Cover the pot and simmer gently for 1.5 to 2 hours, stirring occasionally, until the pork is fork-tender and the flavors have deeply melded together.

Remove the bay leaf and taste for seasoning, adding a pinch of salt only if necessary, as the meats and sauerkraut are usually salty enough. Serve hot with crusty sourdough or rye bread to soak up the rich, savory broth.