How many times have you read a recipe for some kind of steak that instructed you to slice it against the grain, without actually explaining what that means?

For that matter, how many times have I written those words without bothering to explain what they mean?

Well here, once and for all, is the explanation.

To begin with, you have to understand what we mean by the grain. And the best way to understand it is by looking at a steak with very pronounced grain, like a flank steak or skirt steak.

Indeed, these are the kinds of steaks where the recipe is likely to call for you to slice them against the grain.

Now, if you don't have a steak right in front of you, take a look at the picture above. You can very clearly see the individual strands of meat that run lengthwise along the steak. That is the grain.

You can also see that the knife is slicing across those strands, not parallel to them. That is slicing against the grain.

The reason for slicing meat this way is to make it easier to chew. Meat is tough because of the presence of connective tissue made up of a protein called collagen, which happens to be very tough and chewy. There are only three ways to tenderize meat, and each method comes down to softening or breaking up that collagen.

The Grain of Meat is Bundles of Muscle Fibers

Each of those individual muscle strands is actually a bundle of muscle fibers. And each bundle is wrapped in a sheath of collagen.

Collagen can be broken down by slow cooking at low temperatures, which is exactly what happens when we braise meat.

But this doesn't happen right away. It can take hours.

When we cook a steak, we cook it fast and very hot. Which means those collagen sheaths don't have time to soften, so those strands of muscle will still be tough and chewy.

What we're trying to do is shorten those strands as much as possible, so that your teeth and jaws have less work to do. This means that not only is it necessary to slice it against the grain, but you want to slice it as thinly as possible. When you slice against the grain, thinner slices mean shorter strands.

How thin is thin enough? Good question. The answer: As thin as possible. But if you can get it down to half an inch or thinner, you'll be fine.

It's not unlike a mouthful of rubber bands. Not that you would want to eat rubber bands. But if you did, it would be easier to chew them if you sliced them up first so that they were already in short little pieces before you put them in your mouth.

In some cases, specifically with skirt steak, there's an extra step involved. Because skirt steak is so long, and the grain runs across the steak, it's not easy to slice the entire thing against the grain. It's just too long.

But all you have to do is cut it into maybe three shorter sections along the grain, and then slice those sections against the grain.

So that's all there is to slicing meat against the grain. But remember: it's not enough to simply slice against the grain — you need to slice it thinly against the grain.