Combine the olive oil, garlic, herbs, salt and pepper in a small bowl. Rub evenly over roast and let stand at room temperature one hour.
Heat oven to 450ºF (with convection, if you have it) with rack on lowest position. Place roast bone-side down on a wire rack inside a roasting pan. Roast 20 minutes, then reduce temperature to 350ºF (and turn off convection if used). Continue roasting until internal temperature reaches 115ºF for medium-rare. (Check after 1 hour, and continue checking every 15 minutes after that). Transfer roast to a platter and let rest 30 minutes.
While roast is cooking, cook potatoes in a pot of boiling, salted water until tender, about 30 minutes; drain. While roast rests, turn oven back up to 450ºF (again, with convection if you have it). Line baking sheets with parchment paper and drizzle with half of the olive oil and arrange the potatoes in a single layer. Gently smash them using the bottom of a measuring cup or glass, then drizzle with remaining oil and sprinkle with salt. Roast until golden and crispy, 15-20 minutes.