There are two problems that can occur when making this type of pie, weeping and soggy bottoms.
Weeping occurs when those little yellow drops form on the surface of the meringue and/or a layer of moisture develops between the filling and topping. This is caused from a few things – When the sugar in the meringue has not completely dissolved, and the meringue has too much moisture.
Using superfine sugar is your best bet for ensuring all the sugar gets fully dissolved (you don’t have to buy superfine sugar, just run it through your food processor until finely ground). To prevent excess moisture in the meringue, adding adding a bit cream of tartar and beating until it holds stiff peaks will remove excess moisture and add extra stability which can help prevent the weeping.
Also, any air pockets that are left between the filling and the meringue can promote weeping, so be sure to spread the meringue evenly over the hot filling. Have the meringue ready as the filling is cooking – the hotter the filling is when you spread the meringue over it, the less chance weeping will occur. As the heat from the filling with help ‘cook’ the meringue and dry it out.
Soggy bottom crust – pouring hot filling onto a hot crust can create steam between the two, causing the excess moisture to be absorbed into the crust. Allowing the crust to cool completely after pre-baking will prevent this. Another option is to sprinkle some finely ground cookies onto the crust (sugar or gingersnap cookies would be great). This will absorb any excess moisture keeping the crust crisp, in addition to adding a bit of flavor.
For filling, using a heavy-duty non-reactive saucepan (or the acid from the lemon juice will react with the metal and turn the filling grey), whisk together the sugar, cornstarch and salt. Whisk in ¼ cup cold water (warm water will cause clumps) until smooth, then whisk in the remaining cold water.
Over medium-low to medium heat cook mixture, stirring continuously with a spatula once mixture comes to a boil, about 5 minutes. Once it is thick and gel-like, whisk vigorously to smooth out, then cook another minute using a spatula to pull mixture from sides and bottom to prevent scorching. Remove from heat.
In a medium bowl whisk egg yolks until smooth. Slowly ladle in ½ of the hot gel mixture, whisking continuously until incorporated. Repeat with another ½ cup to fully temper the eggs (heating them slowly so they don’t curdle).
Pour the egg mixture into the saucepan, whisking to combine. Return pot to heat and bring back to a boil, about 5 minutes until thick, using a spatula to keep the mixture moving to prevent scorching (you’ll know it’s thick enough when a spatula is pulled across the bottom of the pan, and the filling separates like in the middle picture below). Remove from heat and dot with butter, pushing butter under the surface. Let stand for a minute for the butter to melt.
Gently stir and add in the lemon juice and zest, and pour over the cooled crust.
When whipping the meringue, be sure to stop as soon as firm – stiff peaks form (when the beater is turned upside down, the peaks hold without collapsing). If you over-beat it, the egg whites will break and the mixture will become grainy in texture, dull in color, and won’t be able to hold their peaks anymore like in the picture below (although it will taste just fine).
Lemon Meringue Pie
- 1 cup sugar
- ¼ cup + 2 Tbsp cornstarch
- ¼ tsp salt
- 2 ½ cups cold water divided
- 5 egg yolks*
- 2 Tbsp butter softened & cubed
- 1 ½ Tbsp lemon zest
- 1/3 cup fresh lemon juice
- 5 egg whites
- 1/3- 3/4 cup sugar to taste
- ½ tsp cream of tartar
- Prepare pastry and press into a greased 9” pie plate. Chill for 30 minutes, lightly prick to prevent air bubbles from forming then bake as directed until edges are lightly browned. Allow to cool completely.
- For filling, using a heavy-duty non-reactive saucepan, whisk together the sugar, cornstarch and salt. Whisk in ¼ cup cold water until smooth, then whisk in the remaining cold water. Over medium-low heat cook mixture, stirring continuously with a spatula once mixture comes to a boil, about 5 minutes. Once it is thick and gel-like, whisk vigorously to smooth out, then cook another minute using a spatula to pull mixture from sides and bottom to prevent scorching. Remove from heat.
- In a medium bowl whisk egg yolks until smooth. Slowly ladle in ½ of the hot gel mixture, whisking continuously until incorporated. Repeat with another ½ cup to fully temper the eggs. Pour the egg mixture into the saucepan, whisking to combine. Return pot to heat and bring back to a boil, about 5 minutes, using a spatula to keep the mixture moving to prevent scorching. Once thick, remove from heat and dot with butter, pushing butter under the surface. Allow to stand for a minute for the butter to melt, then gently stir and add in the lemon juice and zest.
- If desired, sprinkle cooled crust with ¼- ½ cup of crushed gingersnap cookies (for added flavor and to keep the crust crisp), then pour over filling.
- For the Swiss meringue - Prepare a double boiler with simmering water, making sure that the bowl does not touch the water beneath. In a large bowl whisk egg whites until frothy. Whisk in the sugar 2 Tbsp at a time until you reach your desired sweetness. Place bowl over double boiler and stir gently but constantly – you don’t want to add air to the eggs at this point, just to keep them moving so they don’t cook. Heat until temperature reads between 115-120°F on an instant read thermometer, and sugar is completely dissolved (you can tell by placing a bit of the mixture between your fingers and rubbing them together to feel for any grittiness). Remove from heat and whisk in the cream of tartar. Using a hand mixer, beat until stiff peaks form, about 3 minutes. Take care not to over-beat, or the mixture can ‘break’ and become grainy.
- Spoon meringue onto crust, spreading out to ensure there is no air pockets between the filling and the meringue, and that the meringue sticks to the crusts' edge (to prevent it from shrinking).
- Bake at 425°F for 5-7 minutes or until tips of meringue become lightly golden. Let sit and room temperature for at least 1 hour before serving.