Preheat an oven to 170°C.
Heat half the oil in a large pan and add the beef. Cook for 4-5 minutes, browning all over, then remove from the pan and set aside.
Add the onions and carrots and cook for 3-4 minutes until softened and starting to brown. Return the beef to the pan and cook for a minute or so.
Sprinkle over the Oxo cubes and cook for 2-3 minutes. Add the flour and stir well to coat the beef and vegetables. Cook for a minute keeping it moving so it does not stick or burn. Add the tomato puree and water, bring to the boil and then simmer for 2-3 minutes.
Place into a casserole dish, cover with a lid and place into the oven. Cook for 1 hour and 20 minutes. Whilst the casserole is cooking, mix the grated sweet potato in a bowl with the oil. Season with a little salt and pepper. Remove the casserole from the oven, take off the lid and top with the sweet potato, ensuring it is evenly covered.
Return to the oven and cook for another 40 minutes until the topping is nicely browned. Remove allow to sit for a few minutes before serving.