Sponge: 50gms Rye; 150 brown, 150 white, 200 ml starter, water to make a wet dough (@250-300ml).
Next morning, 10gms salt, 200 white flour, possibly more water, and good 100gms of mixed seeds.
I mix the flours and starter in a large bowl, then add warm filtered water to make a very wet dough. Leave this sponge over night.
Add the salt and remaining flour. Mix well to make a fairly damp dough. When it's sticky, put in a large bowl with olive oil drizzled down the edges to stop it sticking, and drizzle more over top to keep it moist. Cover and leave for at least 5 hours.
Take it out and knead gently to knock it back. Put it in a spring cake tin and leave till doubled in size.
Slash the top, put in an hot oven (220) for 20 minutes. Release the spring tin clips and leave in the oven for another 20 minutes without a tin.