Remove the skins from the sausages and rolll the meat into about 24 balls, slightly smaller than a golf ball.
Warm a little oil in a non stick frying pan over a moderate heat and cook the balls until they colour. Turn them over and continue cooking until they are evenly browned. Tip away any excess fat.
Pour in the beef stock, bring to the boil and allow to reduce a little. Add the cream and the mustard then season with salt and pepper. Continue cooking for 15-20 minutes.
Remove the meatballs to warm bowls and increase the heat under the sauce to reduce a little. Stir in the herbs if using then pour over the meatballs.