Preheat the oven to 180C/350F/Gas 4. Trim the beef of any hard fat and cut into roughly 3cm/1¼in chunks. Season all over with salt and pepper. Heat one tablespoon of the oil in a large non-stick frying pan and fry the beef in three batches over a high heat until lightly browned on all sides, adding a little more oil to the pan when needed. Transfer each batch to a large flameproof casserole once browned.
Reduce the heat and add two tablespoons more oil to the frying pan. Fry the onions for five minutes, or until softened and lightly coloured, stirring regularly. Add the garlic and sprinkle with the cumin, coriander and chilli powder. Cook for 1-2 minutes more, stirring constantly.
Tip the onions and spices into the casserole with the beef. Stir 150ml/5fl oz cold water into the frying pan and stir vigorously to lift the sediment from the bottom. Pour into the casserole.
Add 350ml/12fl oz more water, the tomatoes and chickpeas to the casserole and stir in the honey. Crumble the stock cube over the top, add the cinnamon stick and stir well. Bring to a simmer on the hob, stirring a couple of times. Cover the dish with a lid, transfer to the oven and cook for 1½ hours.
Ten minutes before the time is up, peel the sweet potato and cut into roughly 2.5cm/1in chunks. Peel the apples, cut into quarters and remove the cores. Cut the apples into 2cm/¾in chunks. Trim the coriander and roughly chop half of the leaves.
Carefully take the casserole out of the oven and remove the lid. Stir in the sweet potato, apples, prunes and chopped coriander. Cover once more and return to the oven. Cook for a further 45-60 minutes, or until the beef is very tender. Roughly chop the remaining coriander leaves just before serving.
To make the garnish, cut the apple into quarters and remove the core. Slice each apple quarter lengthways into five. Season with ground black pepper. Melt the butter in a large non-stick frying pan and fry the apple slices over a high heat for 3-4 minutes, or until lightly browned, turning occasionally. Remove from the heat, drizzle with the honey and toss lightly.
Scatter the fried apples over the tagine in the casserole, scatter with roughly chopped coriander and serve.