Cut the meat into neat dice—any bones and trimmings may be boiled (for at least 1 hr.) to make the stock. Finely chop the onions and coarsely chop the apples. Melt the fat in a saucepan and fry the onions until lightly browned. Add the apple and cook with lid on until tender but not pulped. Sprinkle in the flour and mustard and stir and cook gently for 3–4 min. Add the strained stock, bring to the boil and correct the seasoning. Put in the meat and lemon juice and simmer for about ½ hr. Do not allow to boil. The meat may be served on a border of rice or mashed potato, or garnished with sippets of toast.