Old-school ketchup is surprisingly easy to make, however, and there is no particular reason why restaurants, or indeed customers should depend on the big food brands being able to fulfil supply. All you need is tomato paste, glucose, vinegar, sugar and xanthan gum. These ingredients combine to give you perfect traditional ketchup with the exact texture and flavour you’re used to.
Once you’ve got the recipe down, you can experiment with different ingredients like wasabi, Worchestershire garum, mango, citrus… basically whatever you think of can enhance your ketchup.