Preheat your oven to 425°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
In a small bowl, whisk together 0.5 tablespoons of olive oil with the minced garlic, chopped rosemary, thyme, sea salt, and black pepper to create a thick herb paste.
Pat the beef tenderloin dry with a paper towel to ensure a good sear, then rub the herb paste evenly over all sides of the meat.
Clean and cube the red potato into half-inch pieces and trim the woody ends off the asparagus spears.
Toss the potato cubes and asparagus in the remaining 0.25 tablespoons of olive oil with a small pinch of salt until lightly coated.
Place the beef tenderloin and the potatoes on the prepared baking sheet, ensuring the potatoes are spread out in a single layer to allow for maximum crispiness.
Roast for 15 minutes, then add the asparagus to the tray and continue roasting for another 8 to 10 minutes until the beef reaches an internal temperature of 135°F for medium-rare.
Remove the tray from the oven and transfer the beef to a cutting board, letting it rest for at least 10 minutes to allow the juices to redistribute before slicing into thick medallions.