Directions

1. Sift the sugar and juice the lemons.
2. Set up the double boiler by putting 2 inches of water in the pot. While it comes to a boil, get the other ingredients ready in the mixing bowl.
3. Whisk the eggs, yolk, and sugar until thick and pale.
4. Add the lemon juice, yuzu juice, and salt. When the water comes to a boil place it on the pot.
5. Cook on medium heat, whisking constantly, until the mixture becomes thick. About 10-15 minutes. It should coat the back of a wooden spoon and leave a clear pass if you run a finger through it. If using a thermometer, it should register 170F (75C).
6. Remove from heat and cut the butter from the fridge into 1 inch cubes. Add the cold butter 1 block at a time, whisking so it dissolves. Take your time doing this, the whisking makes an airy/light texture.
7. Move the mixture into a glass jar and let it cool to room temperature.
8. Once cool, pour into the baked and cooled sweet pastry until it reaches the lid of the tart.
9. Refrigerate for at least 4 hours until chilled and set. Overnight being the best.
10. [Optionally] garnish with whipped cream and/or the black sesame meringue.