Lemon Pie

A flour-thickened lemon filling of the kind that predates the cornstarch pie. The proportions are written for two 9-inch pies, and the meringue instructions assume knowledge the book does not spell out.

• The hinge: cook the flour outOnce the boiling water goes in, the filling must actually reach a full boil and hold it a minute or two while you stir. Flour thickens only when its starch gelatinizes, and underboiled flour leaves a raw, pasty taste that lemon juice makes worse.
• Temper, don't scrambleStirring the yolks, sugar, flour and lemon juice with a little cold water first is the whole point of that step; it makes a slurry that will not curdle. Add the 3 cups of boiling water in a thin stream while whisking, then return the pan to the heat.
• Five Roses flourA Canadian hard-wheat all-purpose flour. Ordinary all-purpose works; 4 tablespoons for 3 cups of liquid gives a soft, spoonable set rather than a sliceable one, so expect a looser pie than a modern cornstarch version.
• "Piece of butter"Read as about 2 tablespoons. The recipe stirs it in with the yolks, sugar, flour and lemon juice at the start. It is there for gloss and mouthfeel, not structure.
• SugarTwo cups across two pies is sweet by any standard, and juice from two lemons is only about 6 tablespoons. Taste the hot filling before it goes into the shells; more juice, or the zest of one lemon, brings it back into balance.
• The meringue needs an ovenThe book says only to add sugar and spread it on. Allow 2 tablespoons sugar per white, spread it so it touches the crust all round to stop shrinking, and bake at 350F for 12 to 15 minutes until the peaks are browned. Raw meringue will weep and slide.
• Baked crustsBoth shells must be fully blind-baked and cooled before filling, since nothing goes back into the oven except the meringue.
• Yield and settingTwo pies; the recipe does not say what size. Chill thoroughly before cutting; the filling firms as it cools, though with only 4 tablespoons of flour it will stay on the soft side.