Roll out the pastry on a floured surface and line into a 27cm loosebottomed flan tin. Chill for 30 minutes.
Preheat the oven to 190ºC / 375ºF / Gas mark 5. Line the pastry case with greaseproof paper. Fill the case with baking beans, dried beans or rice. Bake in the oven for 10 minutes, then remove the beans and paper and set the part-baked case aside. Lower the oven temperature to 180ºC / 350ºF / Gas mark 4.
In a large bowl, beat together the almonds, sugar, lemon rind, eggs, oil and orange juice until smooth. Spoon into the pastry case.
Halve, peel and core the pears and cut across into thin slices, keeping the shape of the pear halves. Brush with a little lemon juice to prevent the pears discolouring. Lift each half on top of the almond mixture, pressing down lightly so the slices fan out.
Bake for about 40 minutes or until the almond filling is golden brown and set. Remove from the oven, warm the jam in a small pan and brush over the tart. Serve warm or cold.