The Ribeye cap steak (Spinalis Dorsi) is one of the most tender and flavorful cuts of steak you can buy. When you look for them you may be looking for some thin looking strips about 2" or so wide and 8" or so long. Other times the butcher may have them rolled up to make a little round looking steak and you may even get them to custom cut a whole cap for you.
Like so many beef cuts this steak has many names. It is also referred to as a dorsi cap, spinalis ribeye or in France it is named a calotte steak. I even found one site that referred to the "rolled up" version as a pinwheel prime ribeye cap steak. Be a little careful if you just look for "pinwheel steaks" because that name is also used for rolled up strips of flank steak.
Look for this cut in your local butch shop. It is not an inexpensive cut. Costco does sell the cap steak sometimes and the last price I saw it for was about $18.99lb. If you are feeling flush you can purchase the whole cap at Snake River Farms for $129.00 for 20 ounces.
This steak should be grilled or broiled but grilling tends to show this cut at its best. Jess Pryles, self described carnivore and cookbook author suggests the best way to prepare this cut is to "dry brine" it (salt as you would prior to grilling but refrigerate for 3 days before using then use the "reverse sear" method. You can read about this method here.
Butter Poached Ribeye Cap Steak - With thyme, shallots and garlic by chef Michael Mina
Prime Ribeye Cap - Smoked and seared with onions and mushrooms. Recipe from Denver BBQ.
Grilled Ribeye Cap With Truffle Salt - With caramelized onion butter and Truffle salt.