The recipe yield is:
("Strong white" flour is the UK term for all-purpose flour.) Mix the yeast in 1/2 C of the water at blood heat, and leave 15 minutes to proof. Sift the mixed wheat and rye flours into a mixing bowl to warm. When the yeast has proofed, make a well in the flour, pour the yeast mixture in, and cover it over with a little flour. Leave for 20 minutes to "set the sponge". When this time has elapsed, begin mixing (or kneading with the dough hook if using a mixer). Add 2 cups of the water, check for texture, and add the rest if necessary. Knead vigorously. If using a dough hook, somewhere about 10 minutes into the process the dough will suddenly change texture and require more flour. Add it (probably about another 150 g). Turn the dough into an oiled bowl to rise. The texture will be somewhat sticky. After allowing to rise for 1-1&1/2 hours, turn out of the bowl, punch down, and divide into two loaves. Turn into nonstick pans (or greased ones) and allow to rise for another hour. Bake at 220C for 35 minutes. Turn out of the pans and allow to sit in the still-hot oven upside down for 5 minutes to harden the crusts. Let sit overnight before cutting.