Peel and roughly chop all the vegetables. Melt the butter and fry the oxtail and vegetables, turning frequently until brown. Add the stock and water with the shin bone; bring to the boil and skim. Cover and simmer gently for 3½ hours. Remove the bones from the oxtail and shred the meat.
Skim again and strain into a clean pan; add the sago and bring to the boil. Simmer gently for a few minutes until the sago is cooked. Season with salt, pepper and mustard. Add the sherry and serve at once with cheese straws or bread sticks.
© 1988 Keith Floyd estate. All rights reserved.