On a large piece of wax paper, we measure out 1 and ¾ cup of flour and put in our food processor. To this, we add the wheat germ, confectioners’ sugar, and ¼ teaspoon of salt. We pulse a few times to mix.
We remove the ice-cold butter from the freezer and add to the processor. We pulse 20 times quickly and check the consistency. We want the butter to be mixed into the flour in clumps the size of peas. We pulse another 10 times, check again, and then another 10 times—at which point the mixture is ready.
We dump the crust ingredients into our oblong baking dish (8.875 inches by 12.625 inches). Using a piece of wax paper, we press the crust across the bottom of the dish and a half an inch up the sides. We bake this in the preheated oven for 15 minutes. We want it golden and fragrant. The crust is set aside for half an hour on a wire rack to cool.
Meanwhile, we get the filling prepared. In a batter bowl, we whisk the eggs, granulated sugar, and the third cup of flour for the filling. Over a clean piece of wax paper, we zest a lemon with our microplane until we have ½ tablespoon.
Then, we place the two lemons on a microwave-safe plate, and microwave for 30 seconds to “get their juices flowing”. We squeeze the lemons into a large measuring cup lined with a small strainer to catch the seeds. We want 3 ounces of lemon juice.
Next, we zest a couple of limes. We want ½ tablespoon of the lime zest as well. We add both zests to the batter bowl.
Again, we want to get the maximum amount of juice from the limes. We place them on the plate and microwave for 30 seconds. We juice the limes to get another 3 ounces of citrus juice. We whisk the combined ¾ cup of lemon and lime juices into the batter bowl. We also add the remaining ½ teaspoon of salt.
We pour the filling onto the cooled crust and bake for 25 minutes, rotating the pan halfway through the cooking time. We want the filling just set in the center. We remove the pan from the oven with pot holders and cool on a wire rack.
We refrigerate until we are ready to serve, then cut them into bars and sprinkle with confectioners’ sugar.