Cuts · UK butchery
Fillet steak
Cut across the psoas major, the muscle that does least work on the animal. The one cut where British and American names agree on the thing while disagreeing on the word.
Known as
The same muscle carries different names in different butchery systems, and some of those names mean different cuts elsewhere. Where a name is ambiguous, BBQHQ says so rather than picking one.
- United Kingdom
- Fillet steak
- United States
- Filet mignon
- Tenderloin steak
What to ask a butcher for
- United States: Fillet steak in Britain; filet mignon or tenderloin steak in the United States.
- United States: Fillet steak.
Where it comes from on the animal
Psoas major (fillet)
Loin · low use · connective tissue: low
A muscle that runs inside the ribcage along the spine and does almost no work, which is the whole explanation for the fillet: barely used means barely any connective tissue and barely any marbling, so it is the tenderest cut on the animal and the one with the least fat to protect it from a fire.
Muscles: Psoas major, Psoas minor, Iliacus
Asking a butcher for it
Named the way uk butchery names it. If the counter does not recognise the name, the anatomy is the fallback: ask for the cut by where it comes from.
- What to say
- Fillet steak, or Filet mignon (US), Tenderloin steak (US) depending where you are.
- If that draws a blank
- Ask for loin — the muscle is Psoas major, Psoas minor, Iliacus.
- What to specify
- Thickness, which governs the timing more than weight does — the usual range is 35–50 mm. Typical weight is 180–280 g.
What it is suited to
Derived from how hard the muscle works and how much connective tissue it carries, which is the pairing that decides whether a cut wants a fire under it or beside it. BBQHQ does not rank cuts and does not name a best one.
- Low connective tissue: there is nothing here that a long cook would improve. Direct or two-zone heat, taken off at a doneness rather than at a texture, and every extra minute past that point costs moisture.
- A supporting muscle that does little work, so it is tender to begin with and has nothing to gain from time.
BBQHQ holds cooking evidence for this cut as fillet steak.
What to use instead
BBQHQ has established no substitute for this cut. That is a statement about what has been checked rather than a claim that none exists.
Asking for it in another country
BBQHQ has not established how this cut maps to other butchery systems.
The UK side of these mappings rests on AHDB’s published cutting specifications, which BBQHQ has read. The US side does not: USDA’s Institutional Meat Purchase Specifications and the Beef Checkoff cut pages both refuse automated access, so no mapping here reaches “same cut” across two butchery systems. See the open question.
Typical size
180–280 g