Sift the flour and a pinch of salt into a large bowl. Rub the fat in until the mixture resembles fine breadcrumbs. Sprinkle over enough water to make a firm dough. Wrap and chill for about 20 minutes.

Heat the oil in a large frying pan and add the onions and garlic. Press greaseproof paper down on top of the onions. Cover tightly and 'sweat' the onions over a

gentle heat for about 40 minutes. They should be very soft and well browned. Don't uncover the pan during cooking.

On a lightly floured surface, gently knead the pastry into a neat round. Roll out to a circle about 28 cm (11 inches) in diameter.

Place a 20 cm (8 inch) diameter, 4 cm (1 1/2 inch) deep flan ring on a baking sheet and carefully ease the pastry into it. Neaten the edges.

Prick the base of the pastry case then bake blind with foil and beans in a 200°C (400°F) mark 6 oven for about 10 minutes or until just set. Remove the beans and foil. Bake for a further 8 minutes, or until the pastry has dried out, but not browned.

Meanwhile, put the tomatoes into a small saucepan, stir in the tomato puree and oregano. Boil until the tomato flesh breaks down and the mixture reduces by half, stirring occasionally. Soak the anchovies in the milk for about 10 minutes.

Remove the pastry case from the oven and carefully ease off the metal ring. Stir the tomato mixture into the softened onions and season. Spoon the onion mixture into the pastry case.

Drain the anchovies and arrange over the onion filling to form a lattice. Garnish with olive halves and bake for a further 10 minutes or until really hot. Serve at once.