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 180C/350F/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.