Remove steak from fridge; pat dry and season generously with sea salt and pepper. Keep on the counter so meat can come to room temperature.
Bring a large pot of salted water to a boil over a high flame. Add parsnips and boil until completely tender, about 15-20 minutes. Strain and drizzle with 1 tablespoon olive oil along with a pinch of sea salt. Cover and set aside. Meanwhile, heat 1 tablespoon oil in a large sauté pan over a medium flame until hot. Add steaks to the hot pan. Cook 3 minutes without moving. Flip and sear on the other side: 2 minutes for medium-rare; or 4 minutes for medium. When cooked to your desired taste, remove to a plate and let rest for 5 minutes.
Add broth to the parsnips and purée in a blender or with a hand masher. Season with sea salt and pepper, to taste. In a large bowl, combine arugula and radishes. Whisk vinegar, honey and shallot. Pour over arugula and radishes; and toss. Divide parsnip purée between 2 plates and top with steaks; serve with salad.