Heat a sauté pan with one tbsp of the cooking oil and cook the mushrooms until soft.
Turn the heat off, remove the mushrooms from the pan and add to a mixing bowl with the remaining ingredients, apart from the egg, flour and breadcrumbs.
Mix together and form into four patties, about 8cm diameter. Dip each one in some flour then the egg and then coat well in breadcrumbs.
Add some oil to the sauté pan and heat over a medium flame.
Gently add the fishcakes to the pan (you may need to do this in two sections). Fry for 5 minutes or so on each side until golden brown.
Remove from the pan onto a plate lined with kitchen roll and keep warm while you finish the other fishcakes.
Serve with lemon wedges and watercress or any available greens.