Grease a 20 x 25 cm (8 x 10 inch) roasting tin. Blend the fresh yeast with the warm water. If using dried yeast, sprinkle it into the warm water with the pinch of sugar and leave for 15 minutes until frothy.
Put the flour and salt in a bowl and rub in 15g ( 1/2 oz) of the lard. Make a well in the centre and pour in the yeast liquid. Beat together to make a dough that leaves the sides of the bowl clean, adding more water if necessary. Turn on to a lightly floured surface and knead well for about 10 minutes, until smooth and elastic. Place in a clean bowl. Cover with a clean tea-towel and leave in a warm place for about 1 hour, until doubled in size.
Turn the dough on to a floured surface and roll out to a rectangle about 0.5 cm ( 1/4 inch) thick. Dot one-third of the remaining lard and butter over the surface of the dough. Sprinkle over one-third of the fruit, peel and sugar. Fold the dough in three, folding the bottom third up and the top third down. Give a quarter turn, then repeat the process twice more.
Roll the dough out to fit the prepared tin. Put in the tin, cover and leave in a warm place for 30 minutes, until puffy. (While the dough is rising - preheat oven to 220 °C / 425 °F / Gas 7.) Score the top with a criss-cross pattern with a knife, then bake for about 30 minutes, or until well risen and golden brown. Turn out and serve immediately or leave to cool on a wire rack. Serve plain or with butter.