Ingredients

Step by step

1. Peel then cut the potatoes into 1cm-wide chips. Submerge in a bowl of cold water and leave to stand for at least 1 hour.
2. Meanwhile, start on the gravy. Melt the butter in a large sauté pan on a medium heat. Add the onion and garlic and cook until slightly softened, about 3 minutes. Stir in the flour, cooking it out for 2 minutes until pale golden-brown. Gradually stir in the beef and chicken stocks, followed by the ketchup, balsamic vinegar, Worcestershire sauce and bay leaves. Bring to the boil then lower the heat and simmer until thickened, about 10 minutes. Strain through a fine sieve into a clean pan. Season to taste then cover and set aside.
3. Drain the soaked chips and dry off thoroughly in a clean tea towel. Add vegetable oil to a deep wide pan, to a depth of about 4cm. On a medium hob, heat the oil to 150°C on a cook’s thermometer. Fry a third of the chips at a time until slightly crisp but barely coloured, about 4 minutes. Lift out to a tray lined with kitchen paper; continue until all the chips have had their first fry. Increase the hob heat to high and heat the oil to 190°C. Working in three batches again, fry the chips, stirring often, until crisp and golden brown, about 1-2 minutes. Transfer to fresh paper towels to drain. Once done, sprinkle with salt.
4. Divide the fries between four bowls, layering with the mozzarella. Reheat the gravy so it’s piping hot; add a splash of water if it’s thickened up too much. Pour 1-2 ladlefuls of gravy over each bowl of chips and finish with a grinding of black pepper.