In a hot pan with a little oil, brown the beef skirt lightly on sides for a couple of minutes. Add a pinch of salt to the beef. Do this in batches to avoid crowding the pan. Remove and set aside.
Turn the heat in the pan down to a medium heat. Sauté onion, carrot and celery for a few minutes. Add a little more oil if needed.
Add garlic and cook for a further few minutes, stirring well.
Add tomato puree and cook for a further couple of minutes, stirring well.
In the slow cooker, combine the browned beef and your other sautéed ingredients from the pan. Also add all of the other slow cooker ingredients listed above and stir well.
Cook on low for at least 8 hours.
Carefully remove the beef, shred and then return to the slow cooker. Stir well.
Add a large handful of freshly chopped parsley. Stir and serve.