In a mixing bowl, combine softened butter, olive oil, chopped herbs, minced garlic, lemon zest, salt, and pepper. Mix until well combined.

Spoon the mixture onto a piece of parchment paper and roll into a log shape. Twist the ends to seal and refrigerate until firm, about 1 hour.

Preheat your oven to 400°F (200°C).

In a dry skillet over medium heat, toast the coriander seeds and black peppercorns until fragrant, about 3-5 minutes. Remove from heat and cool slightly.

Using a spice grinder or mortar and pestle, coarsely crush the toasted spices.

Rub the tenderloin with olive oil and season generously with salt. Coat the beef evenly with the crushed coriander and peppercorn mixture, pressing it gently to adhere.

In a large oven-safe skillet, heat a tablespoon of olive oil over medium-high heat. Add the tenderloin and sear on all sides until browned, about 2-3 minutes per side.

Transfer the skillet to the preheated oven and roast for about 20-25 minutes, or until the internal temperature reaches your desired doneness (130°F for medium-rare).

Remove from the oven and let the tenderloin rest for at least 10 minutes before slicing.

Slice the tenderloin into medallions and serve with slices of the herb confit butter on top, allowing it to melt over the warm beef. Garnish with additional fresh herbs if desired.