1. In a large mixing bowl sift the flour
2. Cut the chilled butter into pieces and add to the bowl (use a mixer or if you don’t have one you can simply use a fork)
3. Mix the butter into the mixture until you have a fine crumblike mixture
4. Mix the egg yolk with the water until blended and drizzle over the mixture
5. Add the sugar, lemon zest, and vanilla
6. Continue to stir until the mixture starts to stick together in little lumps
7. Gently press the small lumps of the pastry together using the heel of your hand forming a rough ball
8. Knead gently for a second until smooth and cover with plastic wrap
9. Chill for at least 1 hour if not overnight
10. For the filling in a bowl mix the egg yolks with the sugar and blend
11. In a pot on medium heat add the milk and the cream
12. Next add the mixture of sugar and egg yolks to the pot
13. With a whisk begin to stir in the potato starch, flour, lemon zest and vanilla extract
14. Turn heat to high and continue to whisk for about 3 minutes
15. Once it starts to thicken turn the heat on low and add the pine nuts and continue to whisk
16. Take off the heat and let cool for about 30 minutes to room temperature

Assemble

1. Once the custard is a room temperature fill in the tart and back in the oven at 375 degrees for about 25 minutes.

2. When you see the custard start to brown a bit (see pic) take the tart out and let cool before serving.

3. You can also store in the fridge and serve the next day. Just always make sure to bring it up to room temperature!