Place the flour, sugar, sesame seeds, and salt in a large food processor and blitz until blended. Cut the butter into 1-inch cubes and, with the food processor set to low, feed the butter into the flour mixture. Blitz until the mixture resembles a coarse meal.

In a separate bowl, whisk the egg yolks, heavy cream and vanilla extract together. Return the food processor to its lowest setting and stream the yolk mixture into flour/butter meal. Blitz until a dough forms.

Turn the dough onto a well-floured surface and cut in half. Form both halves into discs and tightly wrap with plastic wrap. Transfer one disc to a freezer bag and freeze for future use. Place the remaining disc in the fridge to chill for 1 hour.

When the hour has elapsed, place the pastry on the counter for 20 minutes. Unwrap the dough and transfer to a floured surface. Using a rolling pin dusted with flour, roll the dough out until roughly an 1/8 of an inch thick. Place a 3-inch tart pan, face-side down, onto the dough and, using a sharp knife, trace a circle around the pan leaving a 1/2-inch border. Place the tart pan right-side up on the counter and lay the circle of dough overtop. Carefully feed the dough into the pan and trim the excess. Repeat until you have 6 filled tart pans. Transfer the pans to the fridge and chill for 30 minutes.

While the tarts are chilling, preheat the oven to 375°F.

Pierce the surface of each chilled tart shell with a fork and cover with a small piece of parchment paper. Fill the tart shells with dried beans and transfer them to a baking sheet. Bake the shells for 20 minutes or until golden brown. Let stand for 10 minutes, then remove the parchment and beans and pop the shells out of their pans. Set aside to cool completely.

Sprinkle the gelatin over the cold water and let sit for 15 minutes.

While the gelatin is softening, pour the milk, salt, and matcha powder into a small saucepan, whisk to combine. Place the pan over medium-low heat and cook until steam starts to form. Remove from the heat.

While heating the milk, separate the egg. Set the egg white aside and add 1/2 the sugar to the yolk. Whisk the sugar into the yolk until pale yellow in color. Whisk a 1/4 cup of the warm matcha mixture into the yolk mixture to temper the egg. Pour the egg mixture into the saucepan and return the pan to the heat. Gently heat the mixture to 200°F, then remove from the heat and whisk in the gelatin. Allow the mixture to cool completely.

Pour the heavy cream and the remaining sugar into a stand-mixer fitted with a whisk attachment. Whip the cream on high until stiff peaks form. Gently fold the whipped cream mixture into the matcha mixture and set aside.

Wipe the stand mixer's mixing bowl clean and add the egg white. Whip the egg white on high until stiff peaks form. Fold the whipped egg white into the matcha mixture.

Pour the mousse into the cooled tart shells and transfer to the refrigerator. Leave the mousse to set for 1 hour.

Pour vegetable oil into a tall glass and place the glass in the freezer. Let chill for 1 hour.

When only 30 minutes of the oil's chilling time remains, pour the lychee syrup and agar agar flakes into a small saucepan. Bring the mixture to a boil, stirring constantly. Remove the pan from the heat and let the mixture cool to 125°F.

Using an eye dropper or a wide-mouth syringe, drip drops of the lychee mixture into the chilled vegetable oil. Small pearls should form and fall to the bottom of the glass.

Drain the caviar using a fine mesh strainer, and gently rinse in cold water. Place the caviar on a piece of paper towel and pat dry. Transfer the caviar to a bowl and set aside.

Place all the ingredients for the whipped cream in a stand mixer fitted with a whisk attachment. Whip the cream on high until stiff peaks form.

Dollop a teaspoon of whipped cream onto each set tart and, using a palette knife, give it a quick sweep to form a whoosh. Sprinkle each tart with lychee caviar and garnish with a bit of citrus zest, if desired.