Line a large sheet pan with foil or parchment paper. Add the rinsed and halved potatoes to sheet pan. Season with oil, salt and italian herbs or oregano (or any other herbs of choice)
Slice off the top of the garlic head about 1/4 inch. Place garlic in a foil tent and drizzle with olive oil. Place garlic in foil in sheet pan with the potatoes and roast at 400F degrees for 25 minutes.
Meanwhile, pat dry the tomahawk ribeye steak with a paper towel. Season both sides of the steak with coarse sea salt and fresh grounded pepper. Wrap the bone in two layers of foil, set aside.
Heat oil in a large skillet (I used a 12'' skillet), when hot add the tomahawk ribeye steak. The bone will likely stick out of the skillet and that's okay. Make sure the meat is in direct contact the hot surface. Sear the steak for about 3 minutes on each side. If possible hold the steak up by the bone and sear the sides too. This should take about 12-15 minutes and the 25 minutes time for the potatoes should be up.
Transfered seared tomahawk steak to oven in the same sheet pan as the potatoes. Turn heat down to 375F degrees and roast for 18 minutes. Give the potatoes a toss too!
When the oven time is up, melt butter in skillet you previously used to sear the steak. To the melted butter add fresh rosemary and all the roasted garlic that you just took out of the oven (make sure to remove the garlic from skin)
Add the ribeye steak to the buttery skillet and baste in melted butter. Do this for about 1 minute on each site. Then transfer ribeye steak to a cutting board. Immediately cover with foil and let it rest for 10 minutes.
After the 10 minutes of rest, you can remove the foil from bone, slice the steak and serve with roasted potatoes.