Your best bet is a stone ground bread flour or hard flour in the US that means finding a local mill. At your standard supermarket a high protein bread flour is your only option if you can find it there. I generally have to venture out to a Whole Foods market to find that as my "local" grocery store doesn't carry it. You could also try Tipo 00, I have run across it in some specialty stores. You are looking for the highest gluten content you can find so that you can get the elasticity you need to make proper strudel.
Yes, and it is very easy. I do it all the time.
You only need a very simple calculation. You don't even have to be precise.
If you do want precision, you will have to find out 1) how much of your flour protein is gluten, 2) how much of your "vital wheat gluten" is gluten, and 3) how much gluten content you need for your recipe. Then use a simple rule-of-three calculation to get the amount needed to add.
I usually don't bother, because 1) and 2) is information which is very hard to find, and due to the large difference in gluten weight and complete weight, imprecision from not using true proportions is minimal. What I do is:
- Look up the protein content of your flour (usually printed on the package), for example 9.6 grams per 100 grams
- Look up the gluten content needed for your bread recipe. If it is not specified, 12.5% is usual for bread flour.
- Add the difference in vital wheat gluten. In the example above, add 2.9 g of vital wheat gluten per 100 g of flour.
This doesn't produce exactly 12.5% gluten content, but I think that it is within the tolerance of most recipes; indeed, not all commercial flours are exactly 12.5%, they vary with brand and season.
I add the powder to the flour and mix it well before making the bread. If I am using a preferment, I add all the gluten to the preferment and make the non-fermenting part with AP flour only, so my gluten can benefit from longer autolysis.
I have no direct comparison with "true" bread flour, as I have never used it. But my breads requiring bread flour turn out good for my standards. There is no problem with bad distribution, the dough turns out very smooth and evenly elastic. There is a pronounced difference to using AP flour only.
Best Answer
Please see this question and the accepted answer. It has a great deal of information.
Without really knowing the reason why there were differences, I learned several years ago that there are most definitely major differences between brands. In my area, for most uses I buy Gold Medal. However, I will never use that for biscuits or rolls. They turn out way too heavy. For making biscuits and rolls I buy either White Lily or Snowflake.
Not sure where you are located, so I have no idea what brands may be available. This page gives some good information and has this chart that lists info for some brands/types of flour.