There are two reasons why I am delighted to feature this book on Cookbook Corner: 1) I am the hugest fan of America's Test Kitchen and all associated publications; 2) I am asked about gluten-free baking so often, and without exhaustive experimentation it is impossible to advise responsibly. This title is the sum total of just such exhaustive experimentation, and anyone interested in gluten-free cookery simply shouldn't be without it.
I have chosen - out of so many problem-solving recipes - instructions for making gluten-free pie dough; yes, of course, the recipe relies on US ingredients and gives US measurements, but this doesn't prevent it from having universal application. Indeed, I used it as a springboard for a very traditionally British Blackberry and Apple Pie which I am proud to add to the recipes on nigella.com.
Perfect pie dough has just the right balance of tenderness and structure. The former comes from fat, the latter from the long protein chains, called gluten, that form when flour mixes with water. Too little gluten and the dough won't stick together; too much and the crust turns tough. So presumably we would face mostly a structural issue with a gluten-free dough, since gluten-free flours are naturally low in protein. As our first step, we swapped in our gluten-free flour blend for the wheat flour in all the pie dough recipes the test kitchen has developed over the years. We produced workable doughs in every case, but an all-butter dough (which includes sour cream for tenderness) had the necessary richness to stand up to the starchiness of the gluten-free flour blend and was clearly the best starting point. Although we weren't surprised to find that the dough was still too soft and lacked structure, we were taken aback by how tough it was; on its own, the sour cream was not sufficient to tenderize a gluten-free dough. We solved the structural problem easily with the addition of a modest amount of xanthan gum, but flakiness and tenderness were still elusive. In an effort to further tenderize our dough, we tested ingredients that are known to tenderize: baking soda, lemon juice, and vinegar. Vinegar was the clear winner, producing a pie crust that was not only tender, but also light and flaky. Like conventional recipes, this pie dough can be prepared in advance and refrigerated for 2 days; however, it is not sturdy enough to withstand freezing.
NOTE: Our gluten-free dough was a lot softer than regular pie dough, but we knew that using extra flour to roll it out would work against us; this additional flour would have no opportunity to hydrate, which meant, as we learned from our testing of muffins and other baked goods, that we'd end up with a gritty texture. Instead, we simply rolled out the dough between two sheets of plastic wrap to prevent sticking and allow for easy transfer to the pie plate.
Single-Crust Pie Dough - makes enough for one 9-inch pie
2½ tablespoons ice water
1½ tablespoons sour cream
1½ teaspoons rice vinegar
6½ ounces Gluten-Free Flour
1½ teaspoons sugar
½ teaspoon salt
¼ teaspoon xanthan gum
8 tablespoons unsalted butter, cut into ¼-inch pieces and frozen for 10-15 minutes
1. Combine ice water, sour cream, and vinegar together in bowl. Process flour blend, sugar, salt, and xanthan gum together in food processor until combined, about 5 seconds. Scatter butter over top and pulse mixture until butter is size of large peas, about 10 pulses.
2. Pour half of sour cream mixture over flour mixture and pulse until incorporated, about 3 pulses. Pour remaining sour cream mixture over flour mixture and pulse until dough just comes together, about 6 pulses.
3. Divide dough into 2 even pieces. Turn each piece of dough onto sheet of plastic wrap and flatten each into 5-inch disk. Wrap each piece tightly in plastic and refrigerate for 1 hour. Before rolling out dough, let it sit on counter to soften slightly, about 15 minutes. (Dough can be wrapped tightly in plastic and refrigerated for up to 2 days.)
Posted by Nigella on the 15th May 2014