Published January 1, 2012. From Cook's Illustrated.
We knew we wanted the ease of a free-form tart, but the typical delicate butter pastry just wouldn’t do. And how could we avoid a soggy vegetable filling?
Many free-form vegetable tart recipes simply borrow a standard pastry dough intended for fruit. But not just any old crust will do. Vegetables are more prone to leaking liquid into the crust or falling apart when the tart is sliced. What’s more, they don’t pack the concentrated, bright flavors of fruit.
We needed a crust that was extra-sturdy and boasted a complex flavor of its own. We also wanted a robust-tasting filling with enough sticking power to hold together when cut.
We knew that the earthy flavor and coarser consistency of whole-wheat flour would bring a nice flavor and hearty crumb to our savory filling. But developing a dough with whole-wheat flour presented a slew of problems.
All doughs get their structure from gluten. And relative to other kinds of flour, whole wheat contains very little, so it produces a heavier dough that is more prone to falling apart. To ensure that our dough would hold its shape, we needed to limit the amount of whole-wheat flour and combine it with white flour. But the more white flour we used the tougher our dough became. The problem was water. Whole-wheat flour needs more water to become fully hydrated, so we’d been using more water in the dough than we would have in an all-white flour dough. This extra liquid was being absorbed by the white flour, thereby creating more gluten and making the dough more susceptible to overworking.
Instead, we took a hands-off approach to mixing and let the flour absorb the water on its own. We barely mixed the dry and wet ingredients together and then chilled the dough briefly. Without any effort on our part, the dough was remarkably supple but not floppy. We took one more measure to ensure that the dough was tender and firm (but not tough). We rolled the dough into a rectangle and folded it into thirds, and then repeated the process twice more. The result: a tender, moist, wonderfully flaky crust that was less apt to shatter when cut.
With our crust down, we turned to the filling. If added raw, the vegetables would leach too much moisture and render the crust soggy. Fortunately, quickly precooking them took only a few minutes and helped concentrate their flavor. To introduce rich, complex flavor and not too much moisture, we worked in a few other elements, like crème fraîche, Dijon mustard, and cheese.list of recipes