Put the mince into a frying pan and cook over a high heat until browned, approximately 6 minutes
Add the leek and onion and cook for a further 4 minutes.
Take off the heat and allow to cool down and go cold.
Place the mashed potato in a large bowl, mix in the sweetcorn, herbs, mint jelly and pepper. Add the mince mixture and the flour. Mix together and slowly add the egg - you might not need all of the egg as you want the mixture to be firm enough to shape.
Place a little flour onto your worktop and on your hands. Divide the mixture into 8 and shape into patty shapes (like fishcakes).
To cook - heat the oil in a frying pan and cook gently, turn over once and cook until both sides are brown and until the inside of the patties are piping hot.