Lemon Berry Tart
makes one 9-inch tart
This tart shell can be made by hand, too.  

Tart shell
1 1/2 cups all-purpose flour
1/2 cup confectioner’s sugar
1/4 teaspoon salt
1 stick plus 1 tablespoon (9 tablespoons; 4 1/2 ounces) very cold unsalted butter, chopped up into small dice
1 large egg

Tart filling
about 1/2 cup raspberry preserve
2 cups lemon mousse, recipe below
assorted berries

1. Throw the flour, sugar, and salt in a food processor and pulse a couple of times until they’re mixed together.
2. Add in COLD butter lumps. 
3. Pulse for a few beats. The mix will look coarse and grainy and a few pea-sized butter bits should remain.
4. Add in egg, pouring it around the whole surface. Pulse again, paying close attention to not let the food processor get away from you. I like to let it come almost to a ball of dough but not quite. Then I knead the rest by hand so I can control it myself. Overprocessing the dough can make it tough.
5. Unload it to a work surface and give to a few turns and presses until it just comes together.  Form the dough into a disk shape.
6. Wrap this disk in plastic and refrigerate for a couple of hours before proceeding. 

7. On a lightly floured surface, roll out the dough. It should be about 3 inches larger in diameter that your tart pan. I have it on a piece of parchment to prevent it from sticking to the table. Sparingly sprinkle with flour as needed to keep it from sticking.
8. Once rolled, drape it over your rolling pin and transfer it to your tart pan. If some pieces break off, no biggie. Press it into your tart pan, making sure to get it to butt up against the corner edges of the pan. If you get tears in your dough, patch it with the scraps. The excess can hang over the edge. Cut away to excess.
9. Prick the tart all over with a fork. These little holes help release the steam that comes from the moisture in the dough.
10. Place the tart shell in the freezer for at least 30 minutes before baking (or longer, if you want to make it the day before). This will help the shell keep its shape when the heat of the oven hits it.
11. Preheat the oven to 375 degrees F.
12. Once you’re ready to bake, remove the shell from the freezer and tightly fit a sheet of tin foil inside the tart shell, taking care to tuck it into the contours. 
 13. Pop the tart on a baking sheet and bake the shell until it’s golden. Mine took about 25 minutes, but don’t go by time, go by color. You’re looking for a lovely golden brown. Let cool completely before filling.

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Lemon Mousse (first make the lemon curd)
makes about a pint

3 large eggs
3 large eggs yolks
1/2 cup sugar
zest of 1 lemon (strip the lemon of zest before you juice, or you’ll be desperately trying to scrape zest off lemon peels, like I’ve been caught doing)
1/2 cup lemon juice (if you want this to taste fresh and vibrant, not chemically and processed, you MUST squeeze your own lemons. Five or six lemons should do it. Taking the time is beyond worth it.)
pinch of salt
2 sticks (8 oz) unsalted butter, cut up into small pieces

First, make the curd:
1. First gather all your ingredients. 
2. Fill a medium pot with a couple of inches of water and bring to a boil. We’re going to improvise a double boiler.
3. Pour the eggs, sugar, lemon zest, lemon juice and salt into a large bowl. (Keep the butter chilled.) Whisk it up.
4.  Set the bowl over the pot with boiling water. This is our faux double boiler.
5. Now whisk like a hurricane, fast and furious. You must whisk the entire time the bowl is over the water. Keep the mixture moving, so the eggs don’t get a chance to scramble. After a few minutes (five?) it starts to get frothy. (If necessary, hold the bowl still by gripping the edge with a kitchen towel.)
6. Keep on whiskin’. After a few more minutes (five more?), it transforms into something creamy. Whisk for another minute just to thicken it up.
7. Take the bowl off the heat. Feed it a handful of butter and whisk it in. The residual heat of the curd will melt it. Keep adding handfuls of butter until it’s all in and fully incorporated. If you still see any little lumps, return to the double boiler for a brief minute, until they disappears, but this is rarely necessary. 
8. Push the curd though a fine mesh sieve to remove the stray bits of scrambled egg that didn’t cooperate. 
9. Put a piece of plastic wrap directly on its surface to prevent a skin from forming and refrigerate. Once it’s completely cold, wrap the whole container tightly and store. (The curd will firm up considerably as it cools. Give it a good stir to loosen it up again before using.) You can store it in the fridge for up to 5 days or freeze for up to a month. To defrost, let the container thaw in the fridge overnight.

Make it a mousse
1 cup heavy cream
1/4 cup sugar
1 1/2 cups lemon curd (recipe above, in case you missed it)

1. In a medium bowl, whisk together the sugar and heavy cream to soft peak stage.
2. Because we whipped air into the cream and made it light and delicate, and because the curd is heavy and dense, we will fold the cream into the curd gradually, so we don’t completely deflate the cream. Scoop a third of the whipped cream into the bowl with the curd. You can eyeball this. It doesn’t have to be exact. Gently fold it in. 
3. Scrape in the rest of the heavy cream and fold it in.
4. Spoon into pretty wares. This can be served right away, or refrigerated for up to 8 hours.

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Assembly:

1. Spread a thin layer of preserve across the bottom of the tart shell.
2. Spoon the rest of the tart shell with lemon mousse.
3. Pile as many berries on top as you see fit.