We've all met our share of tough, soggy and simply unamusing pastries of this ilk. But a good one, pastry that crumbles, flakes and can hold and deliver its filling - sweet or savoury, soft or firm - intact makes for a memorable moment's eating.
To understand what makes pastry react in certain ways, you need to know a little science. Nowhere in cooking is the science more apparent and more important than in pastry-making. Flour and butter are the main ingredients of a shortcrust. Flour contains protein which, when mixed with water, becomes gluten. The gluten in bread or pasta dough needs to be worked thoroughly to create a strong result. With pastry, it's quite the opposite. Like most of us, it responds best to gentle manipulation. And like all of us, it prefers light and careful handling. Delicate handling, in other words, produces a delicate result.
Butter is the shortening agent. When we say "short" in pastry terms, we're talking about the finished pastry's crumbly quality. The more butter, the shorter and flakier the pastry. For a good shortcrust pastry, the ratio is about two parts flour to one part butter. It's not wrong to add more butter if a shorter, crumblier pastry is what you're after. Just remember, the shorter your dough becomes, the more delicate the pastry.
Coldness, be my friend
The number one rule to making a good fine and flaky shortcrust pastry is to chill. And we're not just talking about keeping your cool. Chill your ingredients, too.
Shortcrust has little resilience to outside forces, especially heat. Heat is the enemy of most pastries, so chilling is essential. Always chill your butter, and if the weather is warm, also chill your flour, eggs, water and equipment. For this reason, many pastry-makers work their dough on a chilled marble slab. When butter is warm, it becomes incorporated into the gluten of the flour too readily, creating a less flaky result.
This applies to kneading, too. The more contact the dough has with the warmth of your hands, the more the butter will melt. A kneading action used frequently in pastry-making is called fraisage. This technique sees the the heel of the hand, its coolest part, used to push and smear the pastry gently along a work surface.
There's a key exception to the cold-butter rule. If a pastry case is very delicate, it may not hold its filling. If the filling is heavy or is to be added fresh to a pre-cooked tart case, a little extra strength is required. Beating room-temperature butter in a mixer to soften it before adding to the flour will produce a crisper, less flaky pastry.
Egg yolks and water also affect pastry. Egg yolks contain fat and act as an extra shortening agent but are used more to add colour and richness to the pastry. When you're adding water to pastry, be careful to add only enough to bring the mixture from a crumbly dough to one that can be kneaded and rolled easily. Too much water in the mix means the pastry will steam as it cooks, making for a flimsy result, so add small amounts gradually until you have achieved the right texture.
Give it a rest
Finally, rest your pastry in the fridge after rolling out the dough. This will give the gluten time to relax, creating a more delicate pastry. The chilling also prevents shrinkage during cooking.