Step by step recipe:

1. 30 min.
   The day before baking, or even a several days beforehand, cook the sausages in the oven at 360°F (180°C). The sausages should be nicely browned and, if there are any cooking juices, keep these for adding to the recipe later.
   
   Leave the sausages to cool, then wrap in plastic film and keep refigerated until needed for the dough.
2. 10 min.
   Another thing to do the day before: Peel, rinse and slice 300 g onion thinly.
   
   Put the oinions into a tall container and pour 300 ml red wine over.
3. 3 min.
   Next day, drain the onions...
4. 
   ...and collect the wine they have soaked in.
5. 5 min.
   Melt 30 g butter in a saucepan on medium heat, then add the soaked onions.
   
   Cook for about 5 minutes without colouring.
   
   Leave to cool.
6. 4 min.
   Cut the sausages into slices or small dice.
7. 10 min.
   Put into a food-mixer bowl: 500 g plain white flour (French Type 65), 9 g salt, 15 g yeast, 100 g Soured dough (if possible) and then add the onion-flavoured wine.
   
   If you collected any sausage cooking juices, now is the time to add them.
   
   Knead on slow speed for 10 minutes.
   
   Note: For the best way to knead, see: A few tips for effective kneading at home.
8. 2 min.
   Add the onions and sausage, then knead for a further 2 minutes until these are mixed in.
9. 2 min.
   Gather the dough into a rough ball and transfer to a large clean bowl.
10. 1 hour 30 min.
    Cover with a plastic sheet and leave to rest at room temperature for 1 hour 30 minutes.
11. 5 min.
    After resting, turn the dough out onto the work surface and cut into lumps of about 1 lb (500 g).
12. 2 hours
    Shape into medium-sized loaves and lay in proving baskets.
    
    Cover once more with a plastic sheet and leave to rest for 2 hours.
13. 35 min.
    Preheat the oven to 480°F (250°C). Turn each loaf out onto a baking sheet or your baker's shovel. slash the top and bake with steam for about 35 minutes (do watch for the loaves browning).
14. 
    Leave to cool on a wire or wooden cooling rack.
    
    Your Roscoff loaf is done.