Step 1

Heat oil in a Dutch oven over medium-high heat. Add onion and kale and cook, stirring often, until the onion starts to soften, 5 to 7 minutes.

Step 2

Stir in broth, tomatoes, potatoes, rosemary and pepper. Cover, increase heat to high and bring to a boil, stirring occasionally. Reduce heat and simmer, covered, until the vegetables are just tender, about 15 minutes. Stir in sausage and vinegar and continue to cook, stirring often, until heated through, about 2 minutes more.