Peel and chop carrot and one of the onions. Trim and chop celery. Put into a saucepan with water, bay leaf, peppercorns and lemon juice. Bring to the boil and simmer for 30 minutes. Strain and return to pan.

Cut tripe into pieces. Place in pan with stock and bring to the boil. Skim off any scum, cover and simmer for 1 1/2 hours till tender.

Peel and slice remaining onions. Melt butter in a frying pan, add the onions and fry gently till golden.

Drain the tripe thoroughly, discarding the stock, and cut into thin strips. Add to the onions with plenty of seasoning and fry over a moderate heat for 10 minutes, stirring frequently. Add the parsley and vinegar and mix lightly. Season to taste and pour into a warmed serving dish. Serve immediately with crusty bread.