In a large soup pot, add the sausage over medium-high heat. Cook the sausage for about 10 minutes, breaking it up with a spoon as you go, until crumbly, browned, and cooked through.
Add the onion and stir it into the sausage for two minutes to soften slightly.
Add the kale and garlic and cook, stirring occasionally, for 5 minutes or so to wilt the kale.
Add the tomatoes with juices, beans with juices, and stock to the pot. Stir to combine and taste; add salt to your preference.
Bring the soup to a bubble then reduce the heat to medium-low. Simmer the soup for 10-15 minutes or let sit turned off on the stove until you'd like to eat. If the soup reduces by a lot or gets too thick, add more stock to thin it about about 1/2 cup at a time.
Serve with bread for dunking, and crushed red pepper, fresh parsley, and grated parmesan cheese for sprinkling.