Beef Steak with Mushroom

5 pounds beef prime rib* (if larger, double the spices/seasonings) ▢Sea salt ▢2 teaspoons freshly ground black pepper ▢2 teaspoons fresh rosemary ▢1 teaspoon fresh thyme ▢8 cloves garlic , minced ▢1/4 cup olive oil ▢horseradish , for serving (optional)