Earlier quoted context omitted.
Even easier - only buy and cook/eat things from the supermarket that have one ingredient.
Really? It'd be hard to give up miso, or fish sauce, or chocolate. Or beer. Or gochujang. Cheese. Baking powder. Mustard... I could make some of these things myself, but that's a pretty tall order.
If you want to avoid overly-processed food (like TFA), then do you best to stick to things that have one ingredient.