After reading the excellent recipe  by Pat (proth5),  posted by dmsnyder  I thought i'd give these a go over the weekend and well, it must be a good recipe as even in my ham fisted hands I managed to turn out some very tasty bread, even if I need to watch some more shaping 'n' slashing videos!  I varied it by using 300 grams of flour / 195ml eau (plus the rye starter) and made an overnight sponge with roughly 100g of the flour, starter and water the day before.  The one on the right was baked 1st and was better, must have been the proofing en plastic guttering! I had thought i'd slashed it fairly deeply but the rise was quite impressive.