Melt the butter in a thick-bottomed pan and sweat the onions and thyme with the lid on until soft.
If the onions begin to colour add a tablespoon of water to the pan and stir well.
Then add the flour, stir it in and cook on a low heat for another minute.
Gradually pour in the cider and chicken stock, stirring constantly.
Bring to the boil, add the tripe, season w