Preheat your oven to 400°F (200°C).

In a bowl, combine the crushed cashews and finely chopped coriander. Season the mixture with salt and pepper to taste.

Pat the beef tenderloin dry with paper towels. Rub olive oil all over the tenderloin, then generously coat it with the cashew and coriander mixture, pressing it onto the meat to adhere.

Heat a large oven-safe skillet over medium-high heat. Once hot, sear the beef tenderloin for about 2-3 minutes on each side until browned.

Transfer the skillet to the preheated oven and roast for 20-25 minutes for medium-rare, or until desired doneness. Use a meat thermometer to check (135°F for medium-rare).

While the beef is roasting, prepare the gravy. In a saucepan over medium heat, add a little olive oil and sauté the minced lemongrass and grated ginger for about 2 minutes until fragrant.

Pour in the beef broth, soy sauce, and honey. Bring to a simmer and cook for 5-10 minutes to allow the flavors to meld.

If you prefer a thicker gravy, mix the cornstarch with water to create a slurry, then stir it into the gravy. Cook for an additional 2-3 minutes until thickened.

Once the beef is done, remove it from the oven and let it rest for 10 minutes before slicing.

Serve the sliced beef tenderloin with the velvety lemongrass and ginger gravy drizzled over the top. Garnish with fresh coriander leaves.