ready in 3 h.
Sift the flour and salt into a mixing bowl. Rub in the lard until the mixture resembles coarse breadcrumbs. make a well in the centre.
Cream the yeast with the water in a small bowl and pour it into the well in the centre of the flour, together with 1 egg. Gradually incorporate the flour and beat the dough until it leaves the sides of the bowl clean.
Knead the dough for about 10 minutes on a floured surface until smooth.
Roll out the dough to a rectangle about, about 40cm x 20cm |20" x 8". Trim the edges with a knife.
Soften the margarine with a knife until pliable but not creamy, and divide into 3 portions. Flake one portion and dot it over the upper2/3 of the dough, leaving a 1cm|1/2" border round the edges.
Fold the dough into 3, bringing up first the unbuttered part of the dough, then folding the opposite part over. Give the dough a half turn, and seal the edges by pressing with the rolling pin. Gently press the dough at intervals with the rolling pin and roll out to a rectangle.
Repeat the process with the second portion of margarine, then fold, turn the dough and roll again before adding the last of the margarine. Fold in 3 again. Work quickly to avoid the dough becoming warm and soft and melting the margarine.
Put the folded dough in an oiled plastic bag and chill for 30 minutes.
Roll out the dough and repeat the rolling and folding 3 times more, but without adding any fat. Return to the oiled bag and chill for 30 minutes.
Heat the oven to 220°C (200° fan) 425°F gas 7.
Roll out the dough on a lightly floured surface, to a rectangle about 55cm x 32cm|22" x 13" Cover with oiled cling film and leave to stand for 10 minutes. Trim the edges with a sharp knife, to a rectangle 52cm x 30cm|21" x 12".
Divide the dough in half lengthways. Cut each strip into 6 triangles, 15cm|6" wide at the base.
Beat the remaining egg with a few drops of water and the sugar, and brush some over the triangles. Roll up each triangle loosely, finishing with the tip underneath, then carefully curve the pastry into a crescent shape. Place well apart on ungreased baking trays.
Brush the tops with a little more egg glaze, cover with oiled cling film and leave at room temperature to rise for about 30 minutes until light and puffy.
Brush again with egg glaze, then bake for 15-20 minutes until golden. Cool on a wire rack.