SHORTBREAD CRUST AND TOPPING

1. Use either a 11" x 8" tart pan with a removable bottom, 10" spring-form pan or a quarter sheet pan lined with parchment paper.
2. Preheat the oven to 350°F.
3. Whisk together the salt and flour in a medium sized bowl and set aside.
4. In a stand mixer with the paddle attachment, beat the butter and sugar together on medium/high speed for about 5 minutes until light and fluffy, stop the mixer and scrape the bottom and sides of the bowl a few times. Add the vanilla and mix until fully incorporated.
5. Reduce the speed to low and slowly add the dry ingredients, scraping the bowl a couple of times. Only mix until the ingredients have just come together and the dough is still crumbly so it is easier to distribute in the pan.
6. Set aside 3/4 cup of the dough and spread the rest out in the bottom of the pan.
   Once the dough is evenly distributed in the pan, lightly press the dough into place so it covers the bottom and slightly up the sides of the pan.
7. Bake for about 25 minutes until the shortbread dough puffs up and is a warm golden color all over.
8. While the tart shell bakes, add the oats to the 3/4 cup of remaining dough and use your fingers to smash the dough and oats together into a crumble topping. Place in the crumble topping in the refrigerator until ready to use.

LEMON CURD & RED CURRANT FILLING

1. Combine sugar, lemon zest, and egg yolks in a bowl or the top of a double boiler and whisk together immediately; if you delay, the mixture will coagulate. Place the bowl over a pan or the bottom of the double boiler with about an inch of lightly simmering water and whisk continuously until the sugar dissolves.
2. Add the lemon juice and, still whisking continuously, cook for about 5 minutes. Add the butter and salt, then use a spatula to stir constantly until the mixture is the consistency of sour cream, which will happen at about 170° F. 
3. Strain the curd through a fine mesh sieve. Set aside.
   *If you won't be using it right away, cover with plastic wrap, placing it directly on the surface so the custard doesn't for a skin, and refrigerate for up to 1 week. 
4. Gently toss the red currants with the granulated sugar.

ASSEMBLE & BAKE

1. Spoon the lemon curd into the crust and smooth the top with a spatula. Top with sugared red currants and sprinkle with reserved oat crumble topping. Dot with a handful of currants for color.
2. Bake for 35-40 minutes, rotating the pan halfway through. The topping should be slightly browned and the filling should start to soften and turn a deeper red color.
3. Dust with a sprinkle of confectioners' sugar, then allow to cool slightly before removing from the pan. Slice into 12 equal slices and optionally dust with another layer of confectioners' sugar.