In a small bowl, combine the sea salt, smoked paprika, cayenne, origanum, cumin, sugar and black pepper together.
Trim away the silver skin on the fillet then coat the beef with olive oil and generously rub the spice mix over the beef.
Heat a large frying pan over a high heat, add a splash of olive oil and evenly brown the fillet on all sides. Sear the ends for only a few seconds to seal in the juices.
Transfer the beef to an oven safe dish and roast in the oven for approximately 20 minutes for medium rare beef. Cooking time will depend on the thickness of the fillet.
In the meantime, prepare the salsa verde. Place all the ingredients into a food processor/blender and pulse together. Season with salt and pepper.
Transfer the roast to a chopping board, cover lightly with tinfoil and allow to rest for half it’s cooking time.
Slice the beef tenderloin and spoon over the lemony salsa verde. Serve extra on the side.