Pie
A covered or double-crusted bake where the lid changes the physics: steam that a tart would lose is trapped, and the base pays for it.
Also called fruit pie (INTERNATIONAL), pie crust (US), double crust pie (US)
A pie has a lid. That single difference from a tart drives most of what is distinctive about it.
A COVERED FILLING CANNOT LOSE STEAM UPWARD. Water leaving a hot filling has nowhere to go except sideways and down, into the pastry it is sitting on. A pie base therefore works harder than a tart base against more moisture, which is why pies are more prone to a soggy bottom and why blind baking, a preheated metal sheet, or a hot lower shelf all help in the same way: by getting heat into the base faster than water can soften it.
STEAM VENTS ARE STRUCTURAL. A slit or a funnel in the lid lets pressure escape rather than lifting the lid off the filling or splitting it at the edge. A sealed pie that bursts at the crimp has told you exactly what the vent would have prevented.
THE FILLING IS THICKENED FOR A REASON. Fruit releases a great deal of liquid on heating, and a filling that has not been thickened floods the pastry and runs when cut. Starch, flour or a pre-cooked filling all address the same problem by different routes.
THE PASTRY CHOICE IS NOT ARBITRARY. Short pastry crumbles and is easy to handle; rough puff and flaky pastries give a lighter lid at the cost of a base that is less good at resisting moisture. Many traditional pies use one for the base and another for the lid for exactly that reason.
What it should be like
- Crust
- Crisp base, coloured lid, sealed and vented edges
- Structure
- Holds a slice without the filling running
- Handling
- Kept cold; short pastry warms and becomes unworkable quickly
Soggy bottoms, in the order actually worth trying
Heat first. A pie placed on a metal sheet preheated in the oven gets conducted heat into its base immediately, which is the largest single improvement available and costs nothing.
Barrier second. Blind baking the base, then sealing it with beaten egg that sets into a waterproof film, keeps the filling’s moisture out of the pastry for the part of the bake when the pastry is still setting.
Filling third. A wetter filling is a harder problem than any pastry technique can fully solve; thickening it, cooling it before it goes in, or pre-cooking it removes the water rather than resisting it.
What generally does not help is a longer bake at the same temperature, which dries the top long before it rescues the base.
Related
Part of
Short or flaky paste, distinguished from a tart by having a lid.
Things that go wrong
Harder here than in a tart, because a lid keeps the steam in.
The same stretching fault, in the same short pastry.
What this product needs done
Structure building
The same short paste, doing the same job under a lid.
Gluten inhibition
Overworking is the classic pie-crust fault.
Hydration
Minimal, and cold.
Characteristic ingredients
Plain flour.
Or lard, or a mixture; the choice changes the texture rather than the method.
The traditional British pie fat, and a genuinely different result from butter.
Cold, and minimal.
Techniques involved
Standard for short pastry.
More necessary here than in a tart, because the lid traps steam.