Mix the flour, polenta, orange zest
and thyme leaves together with some
seasoning. Dip the fillets in the beaten
egg then roll in the polenta mix to coat. The fish can now be chilled for a few hours before you're ready to cook.
Heat the butter and olive oil in a large
frying pan until foaming, add the fillets
and lower the heat. Cook for 3 mins on
each side. Meanwhile, wilt the spinach in
a large pan, drain off the excess water,
season and divide between 4 plates.
Serve with the fish fillet on top.