Season the trout with salt, pepper and lemon juice and leave at room temperature for 10 to 15 minutes.
Mix 2 tablespoons breadcrumbs with pecans in a blender. Combine with the remaining breadcrumbs and rosemary. Place on a large plate.
Dredge fish in flour and shake off excess.
Beat egg and water well on a small plate. Dunk the floured fish in egg wash.
Place fish, skin-side up on the breadcrumbs, pressing into flesh.
Heat 1 tablespoon of oil and 1 tablespoons of butter over medium high heat in a large skillet.
Place in 2 fillets and cook until golden brown for around 3 minutes, turn and cook for an additional 3 minutes.
Fish should appear opaque in the centre.
Serve and garnish with lemon and radish slices.