Improv Cooking: Key Lime Realemon Yuzu Bars

I became enamoured with a tiny bag of tiny Key limes the other day at the grocery store. I ran gleefully into the house, showing them off as if I had just sold a company I'd built with my bare hands and then gone out and bought myself one of those gigantic right hand rings. Only I'd rather have Key limes than a ring. They're just so...limey. That is to say, sharp and aromatic, but much more than a regular lime. I converted some of them into Key lime tortilla soup, and then began casting about for a way to hide the rest. Eventually, I settled on the brown sugar shortbread lemon bars from the Tartine cookbook, which looked beautiful in a thickly yellow sort of way. So I started squeezing Key limes. And squeezing. And squeezing. And then, exhausted and in pain from the citric acid, I realized that I had a mere three-quarters of a cup of Key lime juice whereas I needed one cup and two tablespoons. So I topped it off with a quarter of a cup of Realemon and two tablespoons of yuzu juice (see my previous post on the mysteriousness of yuzu). They are buttery crisp, citrusy and smooth. Please try them cold with a cup of hot lemon tea for a real hit on the tongue.
Tartine Lemon Bars on Brown Butter Shortbread

Crust
1/2 cup confectioners' sugar
1 1/2 cups all-purpose flour
3/4 cup unsalted butter

Filling
1/2 cup all-purpose flour
2 1/4 cups sugar
1 cup plus 2 tablespoons lemon juice
lemon zest grated from 1 small lemon
6 large whole eggs
1 large egg yolk
pinch salt

confectioners' sugar for topping

Preheat the oven to 350 degrees Fahrenheit. Butter a 9-by-13 inch baking pan. I generally use the wrapper the butter came in to butter my pan.

Crust: Place the confectioners' sugar and flour into a mixing bowl and stir together. Add the butter and beat on low speed just until a smooth dough forms. Press into the bottom of the baking pan and up the sides by 1/2 inch until the entire crust is 1/4 inch thick. Bake the crust until it is a deep golden brown, 25 to 35 minutes. And I mean a deep golden brown - you really want this crust to be crisp and have a deeply browned butter flavour. The authors of this recipe also sifted the flour and sugar as well as using pie weights while baking, but who has the time? Not me. I also would add a half teaspon of salt to the crust next time to add an extra dimension of flavour to the shortbread crust.

Filling: Place the sugar and flour in a bowl and stir together. Add the lemon juice and zest and stir till the sugar dissolves. In a separate bowl, whisk the eggs and egg yolk with the salt. Add the eggs to the lemon juice mixture and whisk till blended. I had a ton of pits from the key limes, so I let them settle to the bottom of the cup, then used my fingers to strain out the pits from the juice. Also, I didn't use the extra egg yolk. I know the filling would be richer and more custardy, but I just don't know what I'd do with a single egg white hanging around my fridge.

Make sure the crust is hot, either by taking it out of the oven directly or warming it up, then pour the filling into the hot crust. Reduce the oven temperature to 300 degrees Fahrenheit

and bake 30 to 40 minutes until the filling is no longer wobbly in the center.

Cool. Dust with confectioners' sugar. Cut. I used a small tea strainer to dust with sugar, as I don't have a large strainer. Just open it up and snap up some sugar, then knock it against a knife to cover the soft yellowness with sugar drifts.