Cut roast lengthwise along grain into 2 equal, smaller roasts. Rub 1 tablespoon salt over each roast. Refrigerate, uncovered, for 24–48 hours. With oven rack in middle position, preheat oven to 225°F. Heat 2 teaspoons oil in large skillet over high until just smoking. Brown one roast on all sides, 6 to 8 minutes. Remove from skillet. Repeat with 2 teaspoons oil and remaining roast. Cool for 10 minutes. Meanwhile, add garlic, fennel, coriander, paprika, oregano, and remaining ¼ cup oil to food processor. Process, scraping down sides of bowl, to a smooth paste, about 30 seconds. Add pepper. Pulse to combine, 2 to 3 pulses. Using 5 pieces of twine per roast, tie each roast crosswise, at equal intervals, into loaf shape. Place roasts on wire rack in rimmed baking sheet. Rub evenly with spice paste. Roast for 2 to 2½ hours to 125°F for medium rare or 130°F for medium. Remove from oven. Leave on wire rack. Tent loosely with foil. Let rest 30 to 40 minutes. Raise oven temperature to 500°F. Remove foil from roasts. Cut and discard twine. Return roasts to oven. Cook until roasts are well browned, 6 to 8 minutes. Remove from oven. Place on cutting board. Slice ¼-inch thick. Serves 8–10.