Put flour into a mixing bowl. Cut margarine and lard into small pieces with a palette knife, add to flour and rub together with your fingertips, until they look like breadcrumbs.
Make a well in the middle of the flour and add the water bit by bit. Stir with the palette knife after every bit of water you add. When the pastry mix starts sticking together, stop adding the water. Knead lightly on a floured surface until smooth.
Roll out the pastry, fold it in half, place in 20cm flan tin and unfold. Cut off spare pastry.
To make the filling, heat syrup in a saucepan and add the crushed cornflakes. Grate the rind from the lemon and squeeze the juice into the pan and stir until mixed.
Pour the filling into the pastry case.
Bake in the oven for 25 minutes or until the filling is set and golden. Remove from the oven. Enjoy!
With the pastry that you cut off, you could make something to go on top of the tart like a criss-cross lattice. This improves the appearance.