Wagyu Eye Fillet Log SB 4-5: Premium Australian Wagyu at Its Finest

There is a cut that sits at the intersection of lean and luxurious. Not aggressively rich. Not the kind of thing that needs a lot of explanation at the table. The Diamantina Wagyu Eye Fillet Chateaubriand, SB 4-5 is exactly that, a 1kg centre-cut tenderloin that is trimmed, rolled, and ready for whatever you want to do with it. Roast it whole. Slice it into steaks. Build a Beef Wellington around it. It handles all of it.

At Peter Augustus, this cut is prepared by our craft butchers from the Diamantina Wagyu program, which is Stanbroke's own award-winning Australian Wagyu breed. The cattle are raised in Queensland, grain-finished, and graded at a marble score of SB4-5. That is not a number we throw around casually. It means something specific about what you are going to experience when you cook it.

What Is a Chateaubriand, Exactly?

The Chateaubriand is the centre-cut section of the eye fillet, also called the tenderloin. It is the thickest, most uniform part of the muscle. That matters for cooking, because uniform thickness means you get an even result from edge to edge. No thin tail overcooking while the centre is still raw.

The eye fillet runs along the spine and does almost no physical work during the animal's life. That is why it is so tender. It does not carry load or do repetitive movement. The result is a muscle that is remarkably soft even before Wagyu genetics enter the picture.

Add SB4-5 marbling to that and you get intramuscular fat that melts at a low temperature, threading through the lean muscle and adding a buttery quality that standard eye fillet simply cannot match. It is not the same experience. Not even close.

Understanding Marble Score SB 4-5

Wagyu marble scores run from 0 to 10+ which is Stanbroke's own grading designation for their crossbred Wagyu program. A score of 4-5 sits in what a lot of people call the sweet spot. You get genuine Wagyu character, that silky, slightly nutty, almost creamy quality, without the cut becoming so rich that a few bites is your limit.

Higher marble scores like SB8-9 are extraordinary. But they are a different eating experience, almost a different category of food. The SB 4-5 is the grade you reach for when you want Wagyu to be the centrepiece of a proper meal rather than a tasting portion. It still lets the natural beef flavour lead, with Wagyu's signature texture running underneath it.

How to Cook Your Wagyu Eye Fillet Chateaubriand

Wagyu fat renders at a lower temperature than standard beef fat. That is the single most important thing to know before you start cooking. High, fast heat still works for searing, but you need less oil, less time, and more attention to rest. Go slowly and it rewards you. Rush it and the marbling runs out before it has done its job.

Option 1: Portioned into Steaks (Pan-Sear)

Slice the log into portions about 4-5cm thick. That thickness gives you room to build a proper crust without overshooting medium-rare in the centre.

1. 1 Rest before cooking. Take the steak out of the fridge and out of the vacuum packaging 30 minutes before it hits the pan. Room temperature meat cooks evenly. Cold meat does not.
2. 2 Pat dry, season well. Use paper towel to dry the surface completely. Season with good sea salt and cracked pepper. Moisture on the surface kills your crust.
3. 3 Hot pan, minimal oil. A cast-iron skillet works best. Get it smoking hot. Because the Wagyu has its own fat, you only need a very light film of oil. Sear 2 minutes per side for medium-rare. Do not move it around.
4. 4 Rest properly. Off the heat onto a warm plate, loosely covered, for 5 to 8 minutes. This is not optional. The internal temperature keeps rising and the juices redistribute. Cut too early and they run out onto your board instead of staying in the meat.

Option 2: Roasted Whole (Reverse Sear)

For a dinner party, cooking the log whole is the move. It looks impressive, it is easy to carve, and the reverse sear method gives you edge-to-edge evenness that is hard to achieve any other way.

• Low oven first. Preheat to 110°C. Place the seasoned log on a wire rack over a tray and roast slowly until the internal temperature reaches 48°C. Use a digital meat probe. Guessing is not worth it on a cut at this price point.
• Flash sear to finish. Pull it from the oven. Get a heavy pan blistering hot with a knob of butter and a smashed garlic clove. Sear all sides for about 60 seconds each, basting as you go.
• Rest 10 minutes before carving into thick medallions. The result is a consistent blush of pink from edge to edge, with a deep golden crust on the outside.

Option 3: Beef Wellington

The Chateaubriand is the traditional cut for a Beef Wellington, and for good reason. Its uniform shape holds together perfectly inside the pastry, and the SB4-5 marbling adds enough richness to balance the earthiness of a mushroom duxelles. Wrap in prosciutto first to create a moisture barrier, then encase in puff pastry and bake at 200°C until golden. Rest before slicing. For a full recipe walkthrough, visit our Steak School recipe blog.

What to Serve With It

The Chateaubriand does not need much alongside it. Honestly, a sharp green salad and good bread would not be wrong. But if you are building a full plate, lean toward things that work with the richness rather than compete with it.

• Something acidic. A rocket and shaved parmesan salad with a white balsamic dressing cuts through the Wagyu fat cleanly. The contrast is the point.
• Something earthy. Sautéed wild mushrooms deglazed with a splash of dry sherry. Simple, grounding, and it does not steal attention.
• Something starchy. Duck fat potatoes or a smooth potato puree with a touch of truffle oil. Either works. Both are good.

How It Compares to Other Cuts in the Range

If you are weighing up your options, here is a straightforward way to think about it. The eye fillet is your most tender cut. It is not the most flavoursome on its own, but Wagyu marbling solves that. The Diamantina Wagyu range also includes rib fillet and sirloin at SB 4-5, which carry more natural fat and a bigger beef flavour. Those are great for the grill. The eye fillet is the one you reach for when tenderness is the priority, when you are cooking for someone who finds a chewy steak genuinely off-putting, or when the occasion calls for something that looks and eats like a restaurant centrepiece.

If you are newer to Wagyu and want to start with something more approachable in price, the Angus beef collection is worth a look. Excellent quality, very different eating profile, and a solid reference point for understanding what the Wagyu marbling actually adds.

Frequently Asked Questions