How do you turn all purpose flour into bread flour?

Add one teaspoon of vital wheat gluten for each cup of all purpose flour. Make sure you don't get gluten flour, which is simply flour with a high percentage of gluten in it. Vital wheat gluten pure extracted wheat protein and is available in most health food stores. I use it mostly to make seitan because I'm a vegetarian, but it comes in handy when I need to turn some regular flour into bread flour quickly. Hope this helps.