Heat oil in a large stockpot over medium-high. Brown sausage in oil, breaking it up into small pieces until cooked through. Set aside sausage in a covered bowl. Reduce heat to medium and sauté onions in the same stockpot, stirring regularly for 7 minutes until soft and translucent. Add oregano, fennel, and garlic powder, stirring another minute. Add potatoes and stock. Cover, turn heat to high, and bring to a boil; reduce to a simmer and cook until potatoes are fork-tender — start checking after about 7 minutes. Stir in beans, kale, and reserved sausage, cooking until kale wilts and soup is heated through. Stir in vinegar and serve.
Per serving: 336 calories, 12 grams fat (3 grams saturated fat), 761 milligrams sodium, 27 milligrams cholesterol, 34 grams total carbohydrates, 8 grams fiber, 24 grams protein.
