Make a sponge (consistency of fairly thick batter) with yeast, about 2 cups luke-warm water, 1 teaspoon sugar and about 2 cups flour. Leave for about 2 hours.
Rub shortening into flour, add salt and sugar and mix well. Make a little well in center, add sponge. Mix well, adding more warm water (not hot) to make a stiff dough. Knead very well for about 20 - 30 minutes. Cover well and stand in warm place overnight. Next morning it should be double its bulk. Now, without kneading, roll into even-sized buns, pack tightly in greased baking tins. Leave to rise. When double their size, bake in hot oven for 1 hour.
Remove from oven, brush over with 1 tablespoon sugar - 1/2 cup milk (well stirred). Separate rusks while still hot. Leave in cool oven to dry. These will keep for months in air-tight containers.
