I've always thought that the rule of thumb for adding vital wheat gluten to a bread recipe was to add one tablespoon of it per cup of flour called for. A friend is telling me that rather than do that, I should count the vital wheat gluten as flour, and for every tablespoon of it that I add to the recipe, I should subtract a tablespoon of flour from the recipe. Which of us is correct and why?
The bread recipe that I'm following calls for 3 1/2 cups of whole wheat flour and 1/4 cup of dried, nonfat milk powder. I don't have the milk powder, so I thought that the vital wheat gluten would make a decent replacement for it. I also thought that I should increase the flour to 3 3/4 cups and add the vital wheat gluten on top of that, rather than directly substituting it for the dried, nonfat milk (because I've always treated it as an addition/improver).
ETA: I know that both dried, nonfat milk and vital wheat gluten are added to bread recipes to improve the texture of the crumb. What I don't know is how bakers traditionally treat vital wheat gluten: is it counted as part of the flour, or is it considered an addition/improver?