Firstly, heat the olive oil
in a pan over medium heat, and add the onion
, garlic and carrot
and cook until soft. Add the lamb
and beef cube
, then cook until the meat is brown and has a crumbly texture. Stir in the tomatoes, tomato puree, and the corn flour. Simmer
, stirring occasionally, for about 15 minutes, or until thickened.
Meanwhile, peel and chop potatoes. Add the potatoes to a large pot and cover with water. Bring to a boil over medium heat, and cook until soft. Drain the potatoes and add them back to the pan. Mash with a potato masher, stir in the butter and season with salt and pepper, to taste.
Heat broiler to low.
Put the filling into a deep baking dish, then top with the mashed potatoes and put under a warm broiler until the top is brown and crisp.