1. Place meat in a large ziplock bag. Pour the wine and one cup orange juice into the bag. Seal well. Marinate for eight hours or overnight, turning bag occasionally. Drain and reserve liquid. Pat meat dry. Sprinkle with salt and pepper.
2. Pour a few tablespoons of olive oil into a 6-quart (6-liter) pot to coat the bottom of the pot. Set it over medium-high heat. When oil shimmers and flows smoothly, it’s ready. Brown meat on all sides (see note below).
3. Meanwhile, make a paste with the honey, horseradish, and garlic. Remove roast from pot and rub this paste all over the roast. Return to pot. Add reserved wine/juice to pot. Scatter bay leaves around the meat. Add onion if desired. Bring to a boil.
4. Reduce heat and cook for three and half hours, rotating meat occasionally. An hour before the end, add remaining half a cup orange juice, sweet potato, and celery, if desired.
5. Refrigerate meat separately from the gravy and slice when cool. Before serving, gravy can be brought to a boil, then simmered for 10–15 minutes to thicken, and poured over the warmed meat.
Meat needs a few minutes of uninterrupted contact to sear properly. It’ll stick to the bottom of the pot at first (don’t move it! Let it sizzle), and then release naturally when seared. After a few minutes, shake pot. If it releases, it’s ready to be flipped to another side. Searing results in an even browning/caramelization that greatly enhances the flavor of your roast.