I've found that cooking it "backwards" from normal ways (high heat, then slow roast) will give more a red area, with just a slight brown edge. The way Spoon did it is right on�..perfect results. Here's what I've done in the past.
1) Buy your roast 2 days before you cook it
2) Pat it dry as you can, then let it sit in the fridge overnight, uncovered, on a wire rack
3) The day you want to cook it, take it out of the fridge and season it as liberally as you see fit. You may want to consider more salt than you think would be necessary. Press the seasonings into the meat, and let the roast sit on a plate at room temperature all day. Rotate it periodically to get even contact with the juice that draws out.
4) About two hours before you're ready to eat, put a meat thermometer in the center, and preheat the oven for 325 degrees. At this point, the meat should be room temperature. Pat it dry of whatever juice remains.
5) Cook in the low oven until you reach 110 degrees internal (no more, no less). Remove from oven, loosely tent with foil, and crank the oven to about 550.
6) Pop it back in the oven for as long as you want to achieve the outer crust you like. Keep the thermometer in to make sure the temp doesn't get higher than 120.
Let the meat rest at least 20 minutes, then slice as you see fit.