Lemon Meringue Pie

Lemon-and-egg custards and meringue toppings both have deep European roots, but the assembled lemon meringue pie is a 19th-century development. A frequently cited figure is Elizabeth Coane Goodfellow, who ran a celebrated Philadelphia cooking school in the early 1800s and is credited with an early lemon-custard pie; the named lemon meringue pie with its tall whipped-white topping became widespread later in the century as the role of cornstarch in setting fruit fillings was understood, work associated with promoters of cornstarch cookery. The dish has no single uncontested inventor, and the various origin claims are not firmly documented.

A fork through the pie hits three textures: the meringue is soft and faintly chewy like toasted marshmallow, the curd beneath is dense and quivering, and the crust snaps. The lemon hits first and hard — bright, mouth-watering, properly sour — then the sugar of the meringue rounds it off. The curd is smooth and clings to the spoon; the meringue's browned tips taste of toasted sugar. A well-made slice holds its layers upright instead of sliding into a puddle.

The curd is set almost entirely by gelatinized cornstarch, not eggs, which is why it can carry so much acidic lemon juice without weeping; yolks add richness and colour. Strong acid can break starch down, so the cornstarch is fully cooked with water and sugar before the lemon juice is added near the end. The meringue is a foam of egg-white protein unfolded around air bubbles and stabilized by sugar; baking sets the protein and browns the surface through Maillard and caramelization. The two classic faults are 'weeping' (a watery layer between curd and meringue) and 'beading' (sugar droplets on top): both are reduced by spreading the meringue onto hot filling so the underside cooks, dissolving the sugar fully and sealing the foam to the curd.