You’re standing at the Costco meat case or peering through the glass at a high-end local butcher shop. On one side, there’s a vacuum-sealed bag—a "peeled" tenderloin—sitting at a staggering price per pound. Right next to it is the PSMO. That stands for Peeled, Side Muscle On. It looks like a giant, messy prehistoric club. It’s significantly cheaper. Most people walk away because they’re intimidated by the silver skin or that weird "chain" muscle hanging off the side.
They’re literally throwing money away.
Butchering a beef tenderloin is not a surgical procedure requiring ten years of residency. It’s basic mechanics. If you can peel an orange and follow a straight line with a sharp knife, you can save roughly $5 to $10 per pound. On an eight-pound subprimal, that’s a decent steak dinner's worth of savings just for fifteen minutes of work.
Honestly, the "scary" part of the meat is actually where the flavor lives. When you buy a pre-trimmed roast, you lose the scraps. You lose the stir-fry meat. You lose the fat for rendering. When you do it yourself, you get the whole animal’s potential.
The Reality of the PSMO
Before you even touch a knife, you have to understand what you’re looking at. The tenderloin is the psoas major. It sits beneath the ribs, next to the backbone. Because this muscle doesn't do much heavy lifting, it’s incredibly lean and soft. That’s why we love it. But nature didn't package it in a perfect cylinder.
The PSMO comes out of the bag wet. That’s "purge," or just protein-filled water. Don’t wash it. Please. Just pat it dry with a mountain of paper towels. A slippery tenderloin is a dangerous tenderloin.
Gear Check: You Don’t Need a Cleaver
You’ve seen chefs on YouTube using specialized breaking knives. You don't need those. You need a boning knife. Specifically, a flexible one. Brands like Victorinox or Mercer make industry-standard versions for under thirty bucks. The flexibility allows the blade to hug the contours of the meat and the silver skin without gouging out the expensive center.
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If your knife is dull, stop. Sharpen it. A dull knife requires force, and force leads to jagged cuts and ER visits.
Step One: Removing the Chain
The first thing you’ll notice is a long, fatty, ragged-looking strip of meat running down the side of the main muscle. This is the "chain." It’s attached by connective tissue and fat.
Don't even use a knife for most of this.
You can literally pull the chain away with your hands. Just get your fingers under it and tug. It’ll unzip right off the main loin. Near the "head" (the thick end), you might need a small nick with your knife to free it completely.
Pro Tip: Do not throw this away. It’s full of fat and silver skin, yes, but once you trim the junk off, the meat inside is some of the most flavorful on the whole steer. It’s the ultimate "butcher’s snack" for tacos or quick-seared tips.
The Silver Skin Struggle
This is where people get frustrated. Silver skin is elastin. Unlike collagen, it does not melt when you cook it. It stays tough, chewy, and genuinely unpleasant.
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Lay the tenderloin flat. Look for that shimmering, bluish-white membrane.
- Start about an inch or two from one end of the silver skin.
- Slide your knife under the skin, just enough to get a grip.
- Angle the blade slightly upward toward the skin, not downward into the meat.
- Use a sawing motion to slide the knife down the length of the loin.
If you do it right, you’ll produce a long, translucent strip of skin with zero red meat attached. If you see meat on your strip, your angle was too deep. Adjust. It takes practice. Even professional meat cutters at shops like Pat LaFrieda Meat Purveyors emphasize that the goal is "shaving," not "carving."
Dealing with the Head and the Tail
A beef tenderloin is shaped like a baseball bat that someone flattened on one end. You have the "head" (the thick, wide part), the "center cut" (the Chateaubriand), and the "tail" (the thin, pointy end).
The head often has a secondary muscle attached called the wing. Some people leave it on for a massive roast, but for consistent steaks, you should probably trim it back or tuck it.
The tail is a problem because it’s so thin. If you cook it as-is, it’ll be well-done before the center is even warm. The classic move? Fold the tail back onto itself and tie it with butcher’s twine. Now you have a uniform cylinder.
Why "Perfect" Shapes are a Lie
Go to a five-star steakhouse and the Filet Mignon looks like a perfect hockey puck. How? They don't just cut it that way. They use transglutaminase (meat glue) or, more traditionally, they tie the meat extremely tightly and let it set in the fridge.
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In your kitchen, your steaks might look a little lopsided. That’s fine. It tastes the same. If you want that round shape, tie a loop of twine around the circumference of each steak before it hits the pan. It holds the muscle fibers together and ensures even cooking.
Breaking Down the Yields
When butchering a beef tenderloin, expect about 30% waste by weight if you’re being aggressive with your trim. This is the "loss" people fear, but remember, you paid the bulk price.
- The Chateaubriand: This is the center. It’s the prize. Roast it whole or cut it into 8-ounce filets.
- The Medallions: These come from the tapered ends. Great for a quick sear.
- The Tips: These are the odd chunks from the head and the cleaned-up chain. Use them for Beef Stroganoff or stir-fry.
- The Fat: If you’re feeling ambitious, render the fat down to make "beef tallow." It’s better than butter for searing your steaks later.
A Note on Food Safety and Storage
Once you've broken the seal on that vacuum bag, the clock starts ticking. Oxygen is the enemy of red meat. If you aren't cooking the whole thing tonight, you need a vacuum sealer. Wrapping it in plastic wrap is "okay," but it won't prevent freezer burn for long.
If you see a slight grayish tint on the meat after opening the bag, don't panic. That’s just lack of oxygen (deoxymyoglobin). Once it hits the air, it should "bloom" back to a bright cherry red. However, if it smells like sulfur or feels slimy after rinsing/patting dry? Toss it. Your health is worth more than a $60 piece of beef.
Common Mistakes Most Beginners Make
Most people are too timid. They "nibble" at the fat with the tip of the knife. This creates "stair-stepping" on the meat surface, which leads to uneven browning. Use long, smooth strokes.
Another big one: forgetting the "wing" fat. There’s a deep pocket of heavy suet (hard fat) between the head and the main body. Dig it out. It won’t render well and it’s not pleasant to eat.
Actionable Steps for Your First Time
Ready to try it? Don't just wing it. Follow this workflow:
- Clear the deck: You need a massive cutting board. If yours is small, use a clean countertop or a plastic folding table.
- Cold meat is your friend: Do not let the tenderloin sit at room temperature before butchering. Warm fat is like grease; cold fat is like wax. Wax is much easier to cut cleanly.
- The "Three-Pile" System: Set out three bowls. One for "Prime Steaks," one for "Trim/Stir-fry," and one for "Trash" (silver skin and heavy gristle).
- The Finger Test: Run your hand over the meat after you think you're done. Your fingers will feel "hard" spots of connective tissue that your eyes missed.
- Dry Brine: Once butchered, salt your steaks and leave them uncovered on a wire rack in the fridge for at least 4 hours. This dries the surface for a world-class crust.
Butchering a beef tenderloin isn't just about saving money. It's about control. You decide the thickness of your steaks. You decide how much fat to leave on. You become a participant in your food rather than just a consumer. Grab a boning knife and get to work.