Mix all of the ingredients together and store in an airtight container for up to 6 months.
1) Melt the butter in a medium-sized frying pan, add the onion and saute until tender. Add the beef stock and bring to a simmer.
2) In separate bowl, combine the water and cornflour. Stir into the stock and cook for about 1 minute until thickened.
1) Preheat oven to 180C/Gas 4.
2) Bring to the boil a large saucepan of salted water. Add the potatoes and boil, in their skins, until almost done. Allow to cool and cut into long chunky chips, approximately 0.5-1.25cm wide and thick.
3) In a deep fryer, heat the oil to 180C. Add the chips and fry for 5-6 minutes, the potatoes should be limp. Remove the potatoes from the fryer and place on paper towels to drain. Set aside and leave for 1-2 hours at room temperature.
4) Cut the onion into 1.25cm wedges. Just before serving, heat the oil to 190C in the deep fryer, add the potatoes and onions and fry for 3-5 minutes, or until brown. Remove the fried vegetables from the oil, drain on paper towels and, while still hot, season with salt and pepper or house seasoning, to taste.
5) Place the fries in a wide, shallow casserole dish or baking tray and sprinkle with the grated cheese, layering the fries and the cheese. If you want the cheese to be completely melted, bake in a 180C/Gas 4 oven for about 4 minutes after layering the fries and cheese. Remove from oven, top with brown gravy and serve immediately.