Fry the onion in the oil until it is transparent.
Stir in the curry powder and flour and cook gently for 2 minutes.
Add the meat and brown it lightly.
Then mix in the stock, apple and salt.
Bring to the boil, reduce heat, cover the pan and simmer gently for 1 hour or until the meat is tender.
Add the lemon juice just before removing the pan from the heat.