- 1 (2-pound) bone-in rib eye, about 2″ thick
- Kosher salt, freshly ground pepper
- 2 tablespoons vegetable oil
- 2 tablespoons unsalted butter
- 4 oil-packed anchovy fillets, finely chopped
- 2 tablespoons coarsely chopped drained capers
- 1 tablespoon olive oil
- 1 (6–8″ piece) marrow bone, split lengthwise
- 6 radishes, preferably with tops
- 1/2 cup celery leaves or 2 celery stalks, thinly sliced
- 1/4 cup parsley leaves
- 1 tablespoon (or more) fresh lemon juice
- Flaky sea salt (for serving)
- Slices of country-style bread, toasted (for serving)
- Season steak with kosher salt and pepper. Let sit at room temperature 2 hours, or chill up to 12 hours.
- Preheat oven to 300°F. Heat vegetable oil in a large ovenproof skillet, preferably cast-iron, over medium-high. Cook steak until deep golden brown, 5–8 minutes per side. Add butter and spoon over steak a few times. Transfer skillet to oven and roast steak until an instant-read thermometer inserted into the thickest part registers 120°F for rare, 5–8 minutes. Transfer steak to a cutting board and let rest. Increase oven temperature to 425°F.
- Combine anchovies, capers, and olive oil in a small bowl; season with kosher salt and pepper. Spread half of anchovy mixture onto cut sides of marrow bone. Roast bone on a rimmed baking sheet until top is browned and marrow is tender, 10–12 minutes.
- Meanwhile, cut half of the radishes into quarters (leave the tops on, if using); trim and thinly slice remaining radishes crosswise. Toss radishes, celery leaves, parsley, lemon juice, and remaining anchovy mixture in a medium bowl. Season radish salad with kosher salt, pepper, and more lemon juice, if desired.
- Cut steak off bone and slice 1/2″ thick. Transfer meat to a platter, pour pan juices over, and sprinkle with sea salt. Serve alongside marrow bone, radish salad, and toast.