Firstly, place the potatoes in boiling salted water and cook till tender. When done, mash well and add some butter or margarine to your own taste and check for seasoning. Meanwhile, fry the onions off in a little oil until translucent and starting to soften. Add the garlic and fry for another minute. Add the beef and fry until cooked through. Add the tomato puree and stir well into the beef, then add the flour and mix well. It will look like it is starting to catch on the bottom of the pan, but dont worry, you want that. When you get to this point, dont worry about it sticking as the stock will lift this off and it will all add to the flavour. Add the stock a little at a time. How much you add will depend on how thick you want it. I dont like mine too runny so I dont add all the stock. The flour will thicken the sauce and set ity so that you can leave it for 30 mins or so if you want to make it easier to put the mash on top without it sinking into the middle. When you have added the stock and have the consistency you want add the thyme and worcestershire and season. Cook for 5 mins or so then set aside to set, if desired, in an ovenproof casserole. When adding the mash, add to the sides first, then the middle. Smooth over the top and add enough grated cheese to cover. Place in a moderate preheated oven for 15 mins or so until the top is golden and bubbling. Serve with steamed vegetables of your choise.
