Sift the ﬂour and salt into a bowl and rub in the butter and the lard or white vegetable fat until the mixture resembles ﬁne breadcrumbs. Mix to a ﬁrm dough with the egg. Turn out on a lightly ﬂoured surface and knead for a few seconds until smooth. Wrap in plastic wrap and chill for 30 minutes.
Preheat the oven to 200°C. Put the syrup, lemon rind and juice into a small saucepan and heat gently for 1–2 minutes to thin the syrup. Remove from the heat, stir in the breadcrumbs and leave the filling to cool.
Roll the dough out fairly thinly and line a 23 cm pie plate, pressing the dough down gently. Trim off the surplus from around the edge and prick the base lightly with a fork. Knead the trimmings again, roll out and cut out small shapes (hearts, rounds, etc) with a fancy cutter. Alternatively, cut out rounds about 2–3 cm in diameter with a ﬂuted cutter and cut each round into quarters.
Spread the syrup mixture in the lined pie plate, leaving a narrow border around the edge. Brush the shapes with water and arrange them around the edge of the pastry. Put the plate on a baking tray and bake in the centre of the oven for 25–30 minutes, or until the pastry is cooked.
Serve the tart, warm or cold, with whipped cream or custard, if desired.