If you're using premade pastry, go straight to step 3.
- Sift the flour into a bowl with the sugar and salt. Rub in the butter to breadcrumb mixture. Add a little cold water and knead into a dough, adding more water if needed. Wrap and leave to rest in the fridge for 20 minutes.
- Take out for 15 minutes before rolling out. Lightly flour the work surface and roll out into a large rectangle and transfer into a lined tin, including the sides. Bake blind for 20 minutes at 175 degrees C.
- Meanwhile, beat the egg with the sugar and lime. Sift in the flour and mix well. Pour into the baked pastry, then return to the oven for another 20-25 minutes. It should be bouncy to the touch!
- Sprinkle over the coconut then leave to cool before slicing into squares.