1 (1 1/2-pound) porterhouse steak (1- to 1 1/4-inches thick)
2 teaspoons black peppercorns, coarsely crushed (see Cooks' Notes)
2 teaspoons kosher salt
1 tablespoon vegetable oil
3 tablespoons unsalted butter, cut into tablespoon pieces, divided
3 garlic cloves, crushed
2 (4-inch) sprigs fresh rosemary
5 sprigs fresh thyme
1/2 cup medium-bodied dry red wine (such as Chianti, Rioja, or merlot)
1 cup low-sodium chicken broth
Special equipment: ovenproof 12-inch heavy skillet