1. Heat the olive oil in a large Dutch oven over medium-high heat. Add the onion and season with a pinch of kosher salt and a few grinds of black pepper. Cook, stirring occasionally, for 10-12 minutes until deeply golden brown with lightly charred edges.
2. Add the sausage and cook for 4-5 minutes, breaking it into small pieces, until browned. Stir in the garlic and cook for 1 more minute until fragrant.
3. Add the cannellini beans and use a wooden spoon or spatula to mash some of the beans against the side and bottom of the pot. Pour in the chicken stock and season with the kosher salt and freshly ground black pepper. Bring to a boil, then reduce to a simmer.
4. Cook for 10 minutes, stirring occasionally and continuing to mash some of the beans against the side of the pot as they soften, until the broth has thickened slightly.
5. Stir in the kale and simmer for 1-2 minutes until just wilted. Remove from the heat and stir in the white vinegar and parsley. If you prefer a looser broth, stir in a splash more chicken stock or water. Taste and adjust the seasoning with salt and pepper as needed.
6. Serve topped with freshly grated Parmesan and a few parsley leaves. Enjoy!
