Heat oil in a large pot. Add garlic and oregano and cook no more than a minute. Add tomato paste and vinegar, and cook another minute. Add beans and stock and bring to a simmer. Season with salt and pepper. Add kale and simmer, partially covered, for 1 hour. Season, to taste, again with salt and pepper before serving.
Slice baguette on a heavy angle to create long slices. Toast in a toaster or in the conventional oven. Rub once or twice with half a garlic clove. Season a shallow plate of extra-virgin olive oil with salt and dip each side of bread into the oil. Serve as accompaniment to the soup.