Add the oil to a pan then fry the sausages until they are browned slightly
Add the thinly sliced onion, cooking low and slow until they caramelise
Stir the Dijon mustard & garlic granules into the hot stock, then pour over the sausages and onion
Add the dried bay leaves & dried thyme if using, stir then turn up the heat to bring to a rapid boil. Reduce the heat slightly keeping the gravy on a rapid simmer to reduce & thicken (15-20 mins or until the gravy is to the consistency you like)
Add seasoning to taste. Remove the bay leaves and discard before serving