Preheat the oven to 200°C.
1. Crust Grind the seeds in a food processor, add the flour and salt and mix well. Add the butter and pulse until the mixture resembles coarse flour. Keep the food processor running and add the egg yolk and just enough cold water to form a firm dough.
2. Remove from the food processor, shape into a ball and cover in clingfilm. Chill for 30 minutes in the fridge.