FOR THE ROAST:
- 1 tablespoon black peppercorns
- 6 allspice berries
- 2 tablespoons kosher salt
- 5 poun strip loin
- 4 cloves garlic, grated
- 2 bunches rosemary, thyme or savory
- 3 pounds medium Yukon Gold potatoes, peeled
- 3 pounds medium parsnips, peeled, cut in 3-inch lengths
- ¼ pound unsalted butter, melted
- 1 large bunch watercress, for garnish (optional)
FOR THE HORSERADISH SAUCE:
- 1 cup (8 ounces) crème fraîche
- 1 tablespoon Dijon mustard
- 3 tablespoons grated horseradish, preferably freshly grated
- Small pinch cayenne
- Salt and pepper
