Flour Faqs : Why do some recipes specify strong flour for Yorkshire pudding, choux pastry, and flaky pastry?
Strong flour contains more gluten than plain flour. Gluten is the stretchiness in strong flour (see Question 45 for further explanation) which it is essential to have if the trapping of gas is part of the baking process. In these cases the gas is steam. When making Yorkshire pudding, the type of pudding required determines which flour to use. If you want a fairly solid pudding, then use a plain flour; but if you want it to lift more, then use a strong flour which will trap the steam thus causing it to rise in exactly the same way that carbon dioxide is trapped when making bread, thus causing the dough to rise. Exactly the same principle applies to choux pastry and flaky pastry. Don’t forget to put a small slit in the choux pastry when it comes out of the oven to let the steam out, or when it cools down the steam will turn back into water causing the pastry to go soggy.
