Porterhouse Steak with Pan Seared Cherry Tomatoes

Preheat oven to 375 °F with rack in middle. Heat 1 tablespoon oil in a 12-inch heavy skillet (preferably cast-iron) over medium-high heat until it shimmers. Meanwhile, pat steaks dry and sprinkle with kosher salt and 1 1/2 teaspoon pepper. Sear steaks 1 at a time, turning once, until well browned, about 10 minutes total per steak. Transfer steaks to a shallow baking pan (do not clean skillet) and cook in oven until an instant-read thermometer inserted in center of steaks registers 120 °F for medium-rare, about 6 minutes. Transfer to a platter and let stand 15 minutes. While steaks stand, pour off oil from skillet. Add remaining 2 tablespoons oil and heat over medium-high heat until it shimmers, then sauté garlic until golden, about 2 minutes. Transfer with a slotted spoon to a plate. Add tomatoes and thyme to hot oil (be careful; oil will spatter), then lightly season with salt and pepper and cook, covered, stirring occasionally, just until tomatoes begin to wilt, about 2 minutes. Stir in any meat juices from platter, then scatter basil over tomatoes and spoon over steaks.