Slice the linguica into bite-sized pieces.
Prep the onions and garlic and set aside.
Cut the potatoes into bite-sized chunks and set aside.
Coat the bottom of a six-quart sauté pan or Dutch oven with olive oil. Add the linguica to the warmed oil and sauté for about three minutes over medium-high heat.
Remove the sausage to a bowl and set aside.
Add the onions and garlic to the linguica-flavored oil. Sauté over medium heat for about five minutes until the onions are soft and translucent.
Add the potatoes, chicken broth, salt, and crushed red pepper. Bring the mixture to a boil, then reduce heat to low and simmer for about ten minutes.
Remove 1 cup of potatoes and 1 cup of broth from the pot and place them in a food processor. Purée for about 15 seconds until smooth. Set aside. This will naturally thicken the soup.
Add the four cups of hot water to the pot and bring it back to a boil.
Add about half of the chopped kale to the pot and stir it down. As the kale softens and collapses, continue adding the remaining kale until it all fits in the pot.
Stir in the puréed potato mixture and return the cooked linguica to the soup.
Simmer on low heat for about 15 minutes.
Stir in the cannellini beans during the last few minutes of cooking, just long enough to heat them through.
Add chopped parsley if using.
Taste the soup before adding additional salt or pepper. The linguica already brings plenty of flavor, so you may not need much more.
Serve hot with a nice piece of crusty bread.