Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Peel and dice the white potato, carrot, and parsnip into uniform 1-inch pieces.
In a mixing bowl, toss the diced vegetables with half of the olive oil, minced garlic, and half of the rosemary, thyme, and oregano.
Spread the vegetables in a single layer on the prepared baking sheet and roast for 15 minutes.
While vegetables roast, rub the London broil with the remaining olive oil, sea salt, black pepper, and the rest of the herbs.
Heat a heavy skillet over medium-high heat and sear the beef for 3 minutes per side until a deep brown crust develops.
Move the vegetables to the edges of the baking sheet and place the seared beef in the center.
Roast everything together for another 10 to 12 minutes until the beef reaches an internal temperature of 130°F for medium-rare.
Remove from the oven and let the beef rest on a cutting board for 10 minutes to lock in the juices.
Slice the beef thinly against the grain and serve alongside the tender roasted root vegetables.