How to dry-age a steak in 48 hours

There's a little known secret weapon when it comes to aging meat. (Brad Leone)

You could shell out $75 for a 45-day dry-aged rib eye, and then even more for the bottle of red that goes with it. Or you could—stay with me—make it for yourself, at home.

Look, dry-aged meat is amazing and certainly worth buying when you can afford it. But down in the BA Test Kitchen, I’ve been fooling around with a technique that Trentina chef Jonathon Sawyer mentioned to senior food editor Chris Morocco when he visited the kitchen last year, a “fake” dry aging experiment that tastes just as good as dry-aged meat, for a considerably smaller price tag.

The finished product: Tender and juicy. (Brad Leone)

Behold: Koji-rubbed meat.

What is Koji?

Koji is a rice grain that has been introduced with a live culture (Aspergillus oryzae for those of you in the know, bless you) and is one of the main ingredients in making soy sauce and miso paste. When koji is mixed with cooked beans like soy, the live culture helps break down the carbohydrates, amino acids, simple sugars, and proteins in the soybeans.

I decided to try rubbing a cheap and lean steak with some koji rice that I turned into powder using a high-powered blender. Koji, which looks like white rice hiding under a dusty, powdery shell, can be bought online or at most Asian or Japanese supermarkets. In theory, if the live culture is used to break down beans, why can’t it be used to help break down meats?

Why is dry-aging such a big deal?

Dry-aging happens when meat has been left to hang out in a temperature- and moisture-controlled environment. Over time, the meat’s natural enzymes begin to break down the connective tissue and rid the meat of moisture, which results in a rich, nutty, and tender piece of beef. Yes, your pricy steak is essentially starting to decompose. Science!

How do you use Koji?

Rub all sides of the meat (like sirloin or something thin and grainy like skirt or flank steak) generously and then let it sit uncovered on a wire rack in the fridge for 2-3 days. Don’t go too long or the meat starts to get too tough and begins to almost cure. After 12 hours, the meat starts to look like a moist, snow-covered slab of steak (see top photo). The scent is just as rich, nutty, and acorn-like as a steak that’s been dry-aging for over a month, with a touch of sweetness.

Before cooking, rinse the meat thoroughly in cold water to remove all the koji rub that has become a paste, then pat dry. Next, season the meat with salt and sear it in a cast-iron pan. I often will sear the steak quickly and finish it in the oven—basting the steak with melted butter never hurts. You will notice that the steak will caramelize and pick up color much faster than a normal steak.