Heat the olive oil in a heavy bottomed sauté pan or Dutch-oven over medium high heat. Add the crumbled sausage to the pan and cook for about 5 minutes or until the meat is cooked through. Remove the sausage from the pan. Add the chopped peppers to the pan and sauté for another 3-4 minutes. Add the garlic and cook for another minute. Return the sausage to the pan. Add the kale and season with salt and pepper. If the bottom of the pan is dry add a 1/4 cup of water. Cover the pan and lower the heat. Let the kale steam for 5 minutes or until it starts to wilt. Turn the heat off and add the splash of vinegar.