Top, tail and wipe the gooseberries. Put the flour into a bowl and make a well in the middle. Cut the butter and lard in small chunks and put into the well. Pour ⅝ cup (1.5 dl) boiling water quickly over the fat, stir with a knife until it has melted and then pull the flour down into it, continuing to stir with the knife blade until the mixture forms a softish paste. Break off a small piece of the paste and roll out, on a floured pastry board, to about the size of a saucer. Repeat this process but this time roll out the pastry to about the size of the top of a cup. Continue in this way until all the pastry has been used up.
Turn up the edges of the larger pieces of pastry about 1 inch (2.5 cm) all round and cover the bottom of each with gooseberries. On to each put 2 teaspoons of demerara sugar and then a smaller piece of pastry, sealing it to the inner side of the tart, not over the top. Pinch the standing-up edge all round to flute it. Bake at 400°F (200°C, Gas Mark 6) for 20 minutes.