Combine all ingredients except olive oil and butter and season with salt and pepper. Mix well. Divide into 8 balls and flatten into rissole shapes.
Heat half the olive oil and butter in a large frying pan and fry half the rissoles on a low heat until golden and nicely coloured on both sides. You need to make sure they cook through in the middle. If you’re worried, don’t make the rissoles too thick.
Repeat with remaining butter, olive oil and rissoles. Serve with side of your choice.