Buying a whole strip loin is not only a great way to save money on expensive steaks (at Costco, for instance, I can find Prime grade New York strips at less than half the cost of buying individual steaks from Whole Foods or another supermarket that carries Prime meat), it also gives you more control over your final product, allowing you to manage the thickness of each steak as well as the size of the fat cap.
A whole strip can run 10 to 15 pounds, and will yield anywhere between 10 and 20 steaks, depending on how thick you like them (I recommend going at least an inch and a half). Once you've cut your steaks, they can be vacuum sealed or placed into freezer bags and frozen for up to a couple months.
Here's how to do it, step-by-step.
Step One: Dry Carefully
Unpack your strip and place it on a large work surface. Dry it carefully with paper towels and dry the work surface to prevent the strip from slipping around.
Step Two: Trim the Bottom Side
Place the strip fat cap-down and, using a sharp boning knife or chef's knife, trim off any excess connective tissue, silver skin, or fat by first sliding the tip of the knife under the piece you're removing and pulling it gently away from you until the knife cuts free.
Next, grab the flap that you just freed and work the knife in the opposite direction to completely remove it. Repeat this until all of the excess fat and connective tissue is removed.
Step Three: Trim the Fat Cap
The fat cap covers the entire other side of the strip and curls over the edges. Start by trimming the fat backwards off of these edges. There should be an obvious natural seam which will allow your knife to slip in with very little force. Pull back on the fat and continue making small, gentle incisions with your knife until the edges of the fat cap completely free themselves.
Cut through the freed edge to remove excess fat and discard.
Step Four: Flip and Continue Trimming
Flip the strip over so the fat cap is facing upwards. Holding your knife horizontally, continue to trim off fat until there is only a relatively thin, even layer left (the thickness of this layer is up to you—I like to go with around one quarter inch).
Once the fat is trimmed, your strip is ready to cut into steaks.
Step Five: Mark Cuts
Using a ruler or a ruled bench scraper, mark incision points with the tip of your boning knife to use as a guide when cutting steaks. Here I'm marking off one-and-a-half-inch incisions.
Step Six: Cut Steaks
If you have a long carving knife, now would be a good time to use it, though a good chef's knife will work as well. When cutting steaks, the important thing to remember is to never saw back and forth. This leaves an uneven surface on your steaks that carry through all the way through serving. Instead, place the very heel of your blade on the surface of the strip and draw your knife backwards while applying downward pressure.
Continue to pull backwards and downwards until the tip of your blade comes through the meat.
If you have to use multiple strokes to release the steak from the rest of the strip, completely lift your blade up, reset the heel, and pull backwards again. Do not push the blade forward while it is in contact with the meat at any point!
Repeat the process until all of your steaks are cut.