1. Combine the shallot, parsley and thyme in a small bowl. Remove 2 tablespoons of the herb mixture. Add the butter and mash until combined. Refrigerate until 30 minutes before roast is done cooking.
2. With the remaining 2 tablespoons, add the Dijon mustard and 1 tablespoon of the olive oil. Stir until combined.
3. Spread the mustard-herb mixture all over the meat. Refrigerate for at least 1 hour but up to 24 hours.
4. Adjust the oven rack to the middle and preheat the oven to 275.
5. Season all sides of the meat with salt and pepper. Add the remaining tablespoon of oil to a large skillet over medium-high heat.
6. Sear the roast on all sides for 3-4 minutes per side. Transfer the roast to a roasting pan and place in the oven. Cook for 2-2 ½ hours.
7. Remove the roast from the roasting pan and spread with the herb-butter mixture. Tent the roast with aluminum foil and let rest for 20 minutes. Cut into slices and serve immediately.