Passion fruit works so well with the lemon, intensifying the tangy flavor.
Make the pastry as described below, leaving to chill for 30 minutes before using.
Preheat the oven to 350 degrees F. Line the tart tin and bake 'blind'.
Cook's Note: Blind Baking. To pre-bake a pastry shell before adding filling, first chill the pastry, and then line your pan. Line the pastry with foil, parchment or greaseproof paper, leaving plenty to come up the sides. Fill with baking beans (alternatively, for a really smooth finish use plastic wrap to line the pastry: place 2 sheets over the pastry, add the beans and bring the edges into the center.) Whichever method you choose, bake 'blind' in a 350 degree F, oven for 15 to 20 minutes, or until the pastry feels dry.
Remove the paper and beans, brush with a little leftover beaten egg and return to the oven for 2 minutes. If there are any little holes or cracks in the pastry, just patch it up with any leftover raw pastry before you return it to the oven. Remove from the oven and set aside in the pan while you make the filling. The pastry can be baked a day in advance and kept covered until you need it.
For the filling, cut the passion fruit in half and, using a teaspoon, scoop out the pulp from the center and push through a sieve, reserving the seeds in the sieve for later.
Place the eggs, egg yolk, lemon zest and sugar in a bowl, and whisk for a couple of minutes, or until the egg is all broken up.
Add the cream, lemon and orange juice, and the strained juice from the 2 passion fruit. Mix well, skimming off any froth from the top of the mixture.
Carefully pour the filling into the cooked pastry shell so it does not spill. Sometimes I pour in the filling when it is sitting on a rack in the oven to avoid spilling it.
Clean about 10 of the passion fruit seeds by removing them from the membrane that surrounds them, and put to one side.
Reduce the oven temperature to 325 degrees F, and bake for 20 minutes, then place the passion fruit seeds on top. Bake for another 5 to 15 minutes, or until the filling has just set in the centre - it should only wobble very slightly when you take it out of the oven.
Remove from the oven, and allow to cool for about 15 minutes, before removing the tart from the pan and transferring to a plate or cake stand. When it is cool, dust a little confectioners' sugar over the top, and cut into slices to serve.
Sweet Shortcrust Pastry:
Put the flour, sugar, and butter in a food processor and whiz or pulse briefly. Add half the beaten egg and continue to whiz. You might add a little more egg, but not too much as the mixture should be just moist enough to come together.
If making by hand, rub the butter into the flour until it resembles coarse bread crumbs. Then, using your hands, add just enough egg to bring the dough together. With your hands, flatten out the ball of dough, until it is about 3/4-inch thick, and then wrap in plastic wrap or place in a plastic bag and leave in the refrigerator for at least 30 minutes or, if you are pushed for time, in the freezer for 10 to 15 minutes.