Make your "sponge" first...
250g Rye flour
1 Roasted Beetroot mashed (or 50g Beetroot Powder)
2g Dried Yeast
310g Cold Water
Mix with fork into thick batter. Leave covered for 12hours (roughly)
Mix together sponge with:
250g Rye flour
5g dried yeast
10g Salt
Knead as normal, shape into ball and let rise for 3-4 hours.
Carefully take out of bowl onto lightly floured (rye) work surface and shape into 1 large loaf or 2 small loaves. Leave to rise for 45 mins - 1 hour then into HOT oven for 10 mins, reduce temp to 200°C and cook til sounds hollow when base is tapped (at least another 25 mins).