Place the basil leaves, parsley leaves, garlic cloves, lemon juice, capers, mustard powder, anchovies, salt and black pepper in a mini chopper. Blitz until finely chopped and you have a green paste. Alternatively, you can use a stick blender. Scrape the Salsa Verde into a small dish.
Use a piece of kitchen paper to pat the cod dry. Season both sides of the cod with salt and black pepper. Spray a large frying pan well with low-calorie cooking spray and place over a medium high heat.
When the frying pan is really hot, add the cod loin steaks and fry for about 3 minutes on one side until lightly golden. Carefully turn the cod over, using a fish slice and fry the second side for about 3 minutes, until lightly golden. Only turn over once to avoid breaking up the cod. The fish will be cooked when it flakes and is opaque throughout. It may need a little longer depending on the thickness of your cod loin steaks.
Carefully transfer the cod onto serving plates using a fish slice. Place a spoonful of Salsa Verde on top of each piece of cod and serve with an accompaniment of your choice.