Remove the prime rib roast from the refrigerator 3-4 hours before cooking. This allows it to come closer to room temperature for more even cooking. Pat the entire roast thoroughly dry with paper towels.

In a small bowl, combine the Kosher salt, freshly ground black pepper, garlic powder, crushed dried rosemary, and dried thyme. Whisk or stir well to combine.

Rub the entire surface of the prime rib roast with olive oil, then generously coat with the herb-garlic seasoning mix. Ensure all sides are well covered.

Preheat your oven to 250°F (120°C). Place the seasoned prime rib roast, bone-side down, on a wire rack set inside a roasting pan.

Insert the probe of your digital instant-read meat thermometer into the thickest part of the roast, avoiding touching any bones.

Roast in the preheated oven until the internal temperature reaches 120-125°F (49-52°C) for medium-rare. This typically takes 2.5 to 3.5 hours, depending on the roast's size and your oven's calibration.

Once the desired internal temperature is reached, remove the roast from the oven. Tent it loosely with aluminum foil and let it rest on your countertop for at least 20-30 minutes. This resting period is crucial for the juices to redistribute and for even cooking.

While the roast is resting, increase your oven temperature to 500°F (260°C). If using a cast-iron skillet for searing, place it on the stovetop over high heat until it begins to smoke lightly.

Carefully transfer the rested prime rib roast to the hot cast-iron skillet (you may add an additional tablespoon of high smoke point oil like grapeseed or avocado oil to the skillet if desired, but often the roast fat is enough).

Sear all sides of the roast, including the ends, for 2-3 minutes per side, until a deep golden-brown and crispy crust forms. Alternatively, if you don't have a large skillet, you can place the roast back into the 500°F oven for 10-15 minutes until a crust forms.

Transfer the seared prime rib roast to a clean cutting board. Let it rest for another 10-15 minutes before carving. During this final rest, the internal temperature will likely rise slightly to 130-135°F (54-57°C) for a perfect medium-rare.

Carve the roast by separating the bones (if bone-in) and then slicing against the grain into desired thickness. Serve immediately.