Lemon squares are one of those things that I could never wrap my mind around. Now that I have a greater knowledge of food than I did when I first tasted lemon squares, I decided to revisit these childhood classics and add my own spin on it. That’s how my strawberry-lemonade squares were created.
The ability of the filling to gel is based on its custard properties and its starch qualities. As you may know, if you’ve read any other posts on my website, custards utilize the proteins in eggs to trap liquid. This trapping occurs upon heating, when the egg proteins denature and then coagulate (form bonds) around the liquid.
The flour added to the filling also enhances gelling. The amylose starched in the flour leak out of the flour particles as a result of heating in the presence of water. These amylose molecules begin form bonds with other amylose molecules and intramolecular bonds when the mixture cools down.
Because starch and the egg proteins both rely on heat, as the mixture (filling) cools, the gel will become stronger. It is integral to not allow the custard to overcook. The filling is ready when the middle of the custard barely jiggles when the pan is pushed. The first sign of overcooking is the formation of large cracks in the custard.
For the Strawberry Syrup
1 lb strawberries
1 cup sugar
1 ½ water
- Place strawberries into a heavy saucepan, add water, and bring to a boil. Stir, reduce heat to low, and simmer until strawberries soften, about 15 minutes.
- Strain juice into a separate saucepan, using a fine mesh strainer; discard strawberry pulp. Stir in sugar until dissolves. Bring strawberry juice back to a boil a second time.
- Reduce heat to medium and simmer for 5 minutes. Skim any foam from the top of the syrup. Turn off heat and let cool to room temperature.
For the Crust:
Vegetable oil, for greasing
1 1/2 sticks unsalted butter, diced
2 cups all-purpose flour
1/4 cup packed light brown sugar
1/2 cup confectioner’s sugar, plus more for garnish
1/4 teaspoon salt
For the Filling:
4 large eggs
3 tbs of granulated sugar
1/3 cup all-purpose flour, sifted
1 teaspoon grated lemon zest
1 1/4 cup strawberry syrup
Juice from 3 lemons
Make the crust: Position a rack in the middle of the oven and preheat to 350 degrees F. Grease a 9-by-13-inch pan with vegetable oil. Cut the butter into chunks and add to flour in a large bowl. Rub/pinch the butter into the flour until it is incorporated throughout and small beads are present. Stir in the salt and sugars. Press evenly into the bottom and about 1/2 inch up the sides of the prepared pan, making sure there are no cracks. Bake until the crust is golden, about 25 minutes.
Meanwhile, make the filling: Whisk the whole eggs, sugar and flour in a bowl until smooth. Whisk in the lemon zest, lemon juice, and strawberry syrup. Remove the crust from the oven and reduce the temperature to 300 degrees F. Pour the filling over the warm crust and return to the oven. Bake until the filling is just set about 27 to 35 minutes.
Let the bars cool in the pan on a rack, then refrigerate until firm, at least 2 hours. Dust with confectioners’ sugar before serving or cover with fruit of your choice
Makes 24 2-inch squares