1. Preheat the oven to 350°. Rub the roast with 1 tablespoon of the olive oil. In a small bowl, combine the ground coriander seeds and paprika with 2 teaspoons of kosher salt and 1 teaspoon of pepper. Rub the spice blend all over the roast.
2. In a medium roasting pan, heat the remaining 1 tablespoon of olive oil. Add the roast and brown it well on all sides over moderate heat, turning with tongs, about 5 minutes. Turn the roast fat side up. Transfer the pan to the oven and roast the meat for 35 minutes, or until an instant-read thermometer inserted in the thinner end registers 120° for medium-rare meat. Transfer the roast to a cutting board and let rest for 20 minutes.
3. Set the roasting pan on the stove over high heat. Add the flour and cook for 2 minutes, whisking constantly. Add the stock and boil, whisking, until the gravy has thickened, 2 minutes. Season with salt and pepper. Slice the roast 1/4 inch thick and serve with the gravy.