bison Flank
Bison Flank Steak
The flank is the abdominal wall — one wide, thin, boneless sheet per side, carrying the coarsest visible grain on the animal. Bison flank has almost no fat to render, so it cooks fast and stops hard at medium-rare. How thin you slice it, and in which direction, matters more than anything you do to it in the pan.
In one line
The grain is visible from across the room, and it decides whether this eats tender.
Buy it if
You want fajitas, stir-fry or sliced steak salad and you're comfortable cooking hot and pulling early.
The flank muscle holds the animal's gut in. It works constantly but gently — no bracing, no propulsion, just sustained low-force tension — and muscle worked that way grows long, parallel, unusually thick fibers with very little fat woven between them.
That is why the grain here is legible from a distance, running corner to corner at an angle rather than straight down the steak. And it's why the grain is the whole cut. A flank fiber runs the full length of the steak. Slice along it and you hand someone a six-inch strand of muscle to break down with their teeth. Slice across it at an eighth of an inch and every fiber in the mouthful is an eighth of an inch long. Same steak, same doneness, completely different eating experience — decided by the knife, not the fire.
So find the grain and note its direction before you cook. A crust hides it, and by the time you're standing over a rested steak with a knife you'll be guessing.
Bison flank is leaner than beef flank, which is already among the leanest steaks on the animal. There is essentially no intramuscular fat to render, and two things follow. It comes up to temperature faster than a beef recipe's timing expects. And there's no fat cushion between a good medium-rare and a dry, faintly livery medium — a window about ninety seconds wide. Dry the surface hard, use the hottest heat you have, two to four minutes a side, and pull at 125–130°F.
On price: there are two flanks per animal and no way to get more. Supply is fixed however popular fajitas and stir-fry become, which is why this stopped being the bargain cut it was a generation ago.
Where it comes from on the animal
| Species | bison |
|---|---|
| Primal | Flank |
| Subprimal | flank (rectus abdominis) |
What else it’s called
How to cook Bison Flank Steak
| Best methods | Grill Pan sear Broil Griddle Sous vide |
|---|---|
| Skip | Oven roast |
| Cook to | 125–130°F, rare to medium-rare. Past 135°F it turns from chewy-good to chewy-bad, and there's no fat in it to disguise the difference. Rest 5 minutes, then slice thin across the grain. |
If Bison Flank Steak is sold out
Cooks like
Flank Steak
The beef version, a little fattier and more forgiving over high heat. Marinate, sear hot, slice thin across the grain.
Common questions
Is London broil a cut of meat?
No. London broil is a method — marinate, broil hot, slice thin across the grain — that US retailers turned into a label. Depending on the counter it gets stuck on flank, top round, or shoulder, which are three different eating experiences at three different prices. Buy by the muscle name, not the label.
What's the difference between flank and skirt?
Different muscles doing different jobs. Flank is the abdominal wall: wide, flat, fairly thick, one per side. Skirt is the diaphragm — a long narrow strip, thinner, coarser still, with noticeably more fat and a stronger flavor. Skirt cooks in roughly half the time, so they are not interchangeable in a recipe, though both demand the same thin cross-grain slice.
Does marinating actually tenderize it?
Barely. Acid and enzymes penetrate only a few millimeters over several hours — the interior of a flank steak never meets your marinade. Marinate for surface flavor and moisture on a cut that has none of its own, and keep it to an hour or two. Long soaks in something sharply acidic turn the outer layer chalky rather than tender.
How do I get slices thin enough for stir-fry?
Freeze the steak for 20 to 30 minutes first — firm meat gives you control a floppy raw steak won't. Slice across the grain, and go thinner than feels necessary, close to an eighth of an inch. Then cook it in seconds rather than minutes; bison sliced that thin is done the moment it loses its raw color.