This recipe is a little fussy, but, oh, so worth it. I like doing everything as much from scratch as possible, but in a pinch, you can easily use a store bought pie crust. I highly recommend the meringue—sans meringue, it isn’t quite the same.
1 1/4 cups plain / unbleached flour
¼ tsp salt
1/3 cup butter
4 tablespoons cold water
Combine flour and salt in a bowl, Add butter and using a pastry cutter or fork, cut in until the mixture is combined and crumbly. Adding 1 tbsp at a time, use the water to slowly moisten the mixture (you might need more or less water, depending on the humidity in your area). It should be a firm dough, but not crumbly, and not wet.
Roll in a ball, then using a rolling pin, roll to the size of your pie plate. Pinch the edges to make the pastry look pretty. Prick the bottom of the pasty with a fork to create vents and prevent bubbling.
Bake at 450°F / 230°C for about 10 minutes till golden. Cool on a wire rack whilst making the filling.
Key lime pie filling:
3 egg yokes
1 cup sweetened, condensed milk (I like this recipe, but you can also use a tin/can of sweetened, condensed milk)
2 1/2 tsp finely shredded lime peel
1/3 cup freshly squeezed lime juice
5-10 drops key lime confectionery oil
2-3 drops green food colouring (if desired)
Beat yokes till thick and lemon in colour. Slowly stir in condensed milk and lime peel. Add the lime juice, confectioner’s oil and food colouring, a little at a time, until combined, beating on slow, being very careful to not over-beat (the lime juice, if beaten too much or too fast can “cook” the yokes—you do not want that!)
Pour mixture into the cooled pie crust.
4 egg whites
2 tsp vanilla
1/2 tsp cream of tartar (a pinch more if you live in a hot climate)
½ cup caster or other fine sugar
Start with egg whites at room temp. Beat egg whites with vanilla and cream of tartare on medium until soft peaks form. Increase speed to high and slowly add sugar, a spoonful at a time ensuring the sugar “melts” into the mixture before adding more. This should take about 5 minutes, and at the end, the peaks should be stiff and glossy.
Spread the meringue over the pie filling, ensuring that it touches the pastry on all sides. Using a butter knife, you can make swirls in the meringue to make it look pretty.
Bake at 350° / 175°C for about 15 minutes, when the meringue starts to brown just a little. Remove from oven and cool completely on a rack. Store in the refrigerator until ready to serve.