Step 1

Blend chile, sour cream, cilantro, horseradish, lime juice, Worcestershire sauce, salt, and pepper in a blender until smooth. Transfer to a small bowl and chill until ready to use.Do ahead: Crema can be made 2 days ahead. Cover and keep chilled.

Step 2

Place a rack in middle of oven and preheat to 325°. Coarsely grind fennel seeds, garlic powder, caraway seeds, thyme, paprika, and peppercorns in a spice mill or with a mortar and pestle. Place roast on a rimmed baking sheet. Rub with oil and season all over with salt. Sprinkle spice rub over, ensuring all sides of beef are coated. Chill roast, uncovered, 8 hours.

Step 3

Heat a dry large cast-iron skillet over medium-high; cook beef until browned, about 4 minutes per side. Transfer skillet to oven and roast beef until an instant-read thermometer registers 120°–125°, about 2 hours. Transfer to a cutting board and let rest 20 minutes.

Step 4

Transfer roast to a platter; tuck bay leaves around if desired. Serve sliced with habanero crema.