Heat oil in large pot. Add garlic and onion. Cook about two minutes on medium-high heat. Add kale, and cook 2-3 more minutes, stirring frequently. Add some broth if kale sticks to pot. Add beans, tomatoes, pepper, herbs, and (remaining) broth. Bring soup to a low bubble, then cover and let simmer for about 30 minutes.
While soup simmers, cook sausage in another pan to render out fat. Remove casing and break up links. Drain meat, stir into soup, and serve. Sprinkle grated parmesan on each serving if using. For a less spicy soup, omit Mexican-style tomatoes and use sweet Italian sausage.