If I am going to eat a lemon square, it had better be good and lemony, and not just some vaguely yellow-tasting thing. And there should be a goodly, thick layer of topping as well. I've put a lot of effort into developing the ideal lemon square; I'm sure you'll figure out some way to thank me. Props go to Ann Hodgman for introducing me to the Sourtastic Secret Ingredient.*
Sourtastic Lemon Squares
Crust:
3/4 cup flour
1/4 cup cornstarch
1 stick cold unsalted butter, cut into cubes
2 tablespoons sugar
1/4 teaspoon salt
Topping:
3/4 cup lemon juice (or lime, if you're so inclined)
1 cup sugar
3 large eggs
2 tablespoons flour
3/8 teaspoon Sourtastic Secret Ingredient*
Powdered sugar
Preheat the oven to 375 degrees. Line an 8x8-inch pan with two 8x12-inch pieces of waxed paper placed one on top of the other and perpendicular to one another, like a Greek cross. You should have a double layer of waxed paper on the bottom of the pan, with a single layer of paper extending up and over the sides. Butter the paper-lined pan bottom.
Whirl up the crust ingredients in a food processor until they are a fine-textured meal. Pour the meal into the pan and press it down firmly all over to form an even layer. Bake for 20 minutes. The crust should be golden, not pale; if it's pale, it will turn gummy once you put the filling on.
While the crust is baking, put all the topping ingredients in the food processor and pulse for a few seconds. Once the crust is done, turn the oven down to 350 degrees. Whirl the lemon mixture around in the food processor for a final few seconds in case it has settled, then pour it carefully over the crust. Put the pan back in the oven and bake for another 20-25 minutes, until the topping is set. Remove from oven and let cool completely. Don't cheat; you'll be sorry.
Once the squares are cool, run a butter knife around between the waxed paper and the pan sides. Now remove the whole batch at once by carefully pulling up on the waxed paper edges. Set the whole thing on a cutting board, cut into squares, and dust with powdered sugar.
Keep them in the fridge. That way, your three-year-old is less likely to pull a chair up, sneak inside without detection, and snarf them all. Plus, they're scrumptious when chilled.
If you're all really good and don't abandon me while I write hard for the next few weeks, I might be persuaded to post my Dulce de Leche Squares recipe sometime soon.
* Sourtastic Secret Ingredient = Citrus salt, a.k.a. citric acid. You can buy it at Middle Eastern specialty stores, or you can stock up on it during canning season (late summer), like I do. It's used to process tomatoes for long-term storage. One time I was checking out at the supermarket, and the cashier said, "Boy, you must can a lot of tomatoes." Nope. But I would never want to be without the option of lemon squares.