Beef Fillet Filled with Kale, Almonds, Feta and Parmesan

For the beef fillet filled with kale, almonds, Feta and Parmesan

• Preheat the oven to 200°C (180° fan)  | gas 6.
• Line a roasting tray with a trivet large enough to hold the beef.
• Using a long sharp knife, make 3 cm | 1.25" incision in the middle of the beef fillet that runs along its length; you can also use a sharpening steel to help bore the hole if you don't have a long enough knife.
• Blanch the kale in a large saucepan of salted boiling water for 1 minute.
• Drain and refresh in iced water before drying thoroughly and chopping.
• Combine with the almonds, Feta, Parmesan, 1 tbsp olive oil, and seasoning in a food processor.
• Pulse a few times until the mixture comes together like a stuffing.
• Pack it into the hole in the beef and then rub the outside of the fillet with the remaining olive oil. Season generously with salt and pepper.
• Tie the fillet at 2.5 cm | 1" intervals with kitchen string.
• Sit on the trivet and roast for 35-45 minutes until the beef registers 60°C  on a meat thermometer for medium-rare meat.
• Cook for longer for more well-done meat.
• Remove from the oven and leave to rest, covered loosely with aluminium foil, as you prepare the sauce.

For the sauce

• Melt the butter in a saucepan set over a medium heat.
• Whisk in the flour and cook for about 1 minute until blonde in colour.
• Whisk in the milk in a slow, steady stream until you have a smooth, slightly thickened sauce.
• Bring to a simmer, whisking frequently, and then reduce the heat and cook for a further 4-5 minutes until thickened.
• Whisk in the egg yolk and then the lemon juice and parsley.
• Continue to cook for a few minutes before seasoning to taste.
• To serve, cut the beef fillet into slices.
• Serve on a bed of the kale with the sauce on the side.
• Season with more salt and pepper, if desired.