Pissaladière

Shortcrust pastry

1. Place the flour, salt, water/oil and butter in a food processor and whiz briefly. Add half the beaten egg and continue to whiz. You might add a little more egg, but not too much as the mixture should be just moist enough to come together. If making by hand, rub the butter into the flour (1) until it resembles coarse breadcrumbs (2) then, using your hands, add just enough egg to bring it together (3). With your hands, flatten out the ball of dough until it is about 2cm (3/4in) thick (4), then wrap in cling film or place in a plastic bag (5) and leave in the fridge for at least 30 minutes or, if you are pushed for time, in the freezer for 10–15 minutes.

For the topping

1. Meanwhile, heat the olive oil in a wide, heavy-bottomed frying pan, then add the onions. (The pan will seem quite full at first, but the onions will melt down considerably after about 10 minutes.) Stir the onions in the oil and cook over a low heat, covered, for at least 20 minutes, stirring continuously and scraping the base of the pan every few minutes.
2. Now add the garlic, herbs and salt, pepper and sugar, and continue cooking for 10 minutes until the onions begin to melt and turn golden. Taste for seasoning, adjusting if necessary, and remove from the heat.
3. Preheat the oven to 180ºC (350ºF), Gas mark 4.
4. Remove the pastry from the fridge, uncover and, with a floured rolling pin, roll out on a floured work surface into a rectangle to fit the Swiss roll tin (23 x 33cm (9 x 13in) Swiss roll tin). Lift it onto the tin and prick the whole base with a fork. Bake in the oven for 10 minutes, then remove.
5. Cover the pre-baked base with an even layer of onions. Arrange the anchovy fillets in a lattice pattern over the onions, placing a whole or halved olive within each diamond.
6. Return to the oven and bake for a further 25 minutes to allow the flavours to blend. Serve hot or cold.