Heat oil in a large Dutch oven over medium-high heat. Add onion; sauté 5 minutes. Add 1/2 teaspoon salt, pepper, and garlic; sauté 1 minute. Remove casings from sausage; add sausage to pan. Cook 5 minutes or until sausage is lightly browned, stirring to crumble. Add potato, 5 cups water, and broth; bring to a boil. Reduce heat, and simmer 8 minutes. Gradually add kale; cook 10 minutes or until tender. Stir in remaining 1/2 teaspoon salt and beans; cook 5 minutes or until thoroughly heated.