Mix the rye flour, boiling water,
treacle, butter, salt and caraway seeds in a large bowl. Leave to cool.
In another bowl, mix the yeast and
lukewarm water and leave to dissolve. Stir into the rye flour mixture.
Stir in just enough plain flour to
obtain a stiff dough. If it becomes too stiff, stir with your hands.
Transfer to a floured surface and
knead thoroughly until the dough is no longer sticky and is smooth and
shiny.
Place in a greased bowl, cover with a
plastic bag, and leave in a warm place until doubled in volume. Punch
down the dough, cover, and leave to rise again for 30 minutes.
Preheat the oven to 180oC/350oF/Gas
4. Dust a baking sheet with semolina or flour.
Shape the dough into a ball. Place on
the sheet and score several times across the top.
Bake until the base sounds hollow when
tapped, about 40 minutes. Cool on a wire rack.