Grease 8 x 400 ml (14 fl oz) clean food cans and line with greaseproof paper that extends above the rims. Grease the paper. Stir the yeast and 1 teaspoon sugar into the milk in a large, warm bowl and leave for 10 minutes or until frothy. Stir in 100 g (3½ oz) of the flour. Cover with clingfilm and leave for 30 minutes.
Add the eggs and yolks, the remaining flour and the sugar, vanilla extract, lemon rind and butter. Mix with a round-bladed knife to make a soft dough, adding a little more flour if the dough feels sticky. Turn out on to a lightly floured surface and knead until smooth and elastic. Leave to rise in a lightly greased bowl, covered with clingfilm, for 2–4 hours or until doubled in size.
Knock back the dough (punch your fist into the risen dough so that it collapses as the air is excluded) and lightly knead in the dried fruit. Cut the dough into 8 pieces and drop into the tins. Cover and leave to rise until the dough almost reaches the rims.
Bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 20–25 minutes or until risen and golden. Leave for 5 minutes, then cool on a wire rack.