Mise en place - Slice the chorizo into quarter-moon shaped pieces. Strip the kale leaves from the stems. Discard the stems and coarsely chop the kale leaves. Trim any blemishes from the sweet potatoes and cut them into medium cubes. Peel and chop the onion. Peel and mince the garlic.
Build the stew - Add the sweet potatoes, and stir to coat with the spices. Add chicken broth, diced tomatoes, and tomato sauce. Bring to a boil, reduce heat to low, cover with the lid slightly ajar, and simmer 15-20 minutes, or until the sweet potatoes are tender.
Finish - Add the kale, cover, and cook 5 more minutes until wilted. Add the vinegar and season to taste with salt and black pepper.