Flap Steak vs Tenderloin — What's the Difference?
Quick Answer
Flap Steak (flap steak (sirloin flap)) and Tenderloin (beef tenderloin) are not the same cut: Flap Steak is sirloin primal (Bottom sirloin, obliquus internus abdominis muscle); Tenderloin is loin primal (psoas major).
Canonical entities: Flap Steak · Tenderloin
Side-by-side
| flap steak | tenderloin | |
|---|---|---|
| Primal | sirloin | loin |
| Muscle / location | Bottom sirloin, obliquus internus abdominis muscle | psoas major |
| Character | A thin, coarse-grained steak from the bottom sirloin. The American name for what the French call bavette d'aloyau. Open grain absorbs marinades extremely well. Popular for fajitas, stir-fry, and carne asada. Often confused with skirt steak but from a different location entirely. | Most tender muscle of the loin; center cuts often sold as filet mignon. |
Key differences
- Different primals: sirloin vs loin.
- Texture and slicing: compare fibrous, grain-heavy cuts vs more tender steak-style muscles based on each cut’s description.
- Retail naming diverges by country—always map through a canonical cut when translating menus or labels.
When to use each
Flap Steak
Pick Flap Steak when you want its specific marbling/texture profile: A thin, coarse-grained steak from the bottom sirloin. The American name for what the French call bavette d'aloyau. Open grain absorbs marinades extremely well. Popular for fajitas, stir-fry, and carne asada. Often confused with skirt steak but from a different location entirely.
Tenderloin
Pick Tenderloin when its primal/muscle traits fit the dish: Most tender muscle of the loin; center cuts often sold as filet mignon.
Flap Steak and Tenderloin are different canonical muscles/primals: Flap Steak is sirloin (Bottom sirloin, obliquus internus abdominis muscle); Tenderloin is loin (psoas major).
Choose based on tenderness, marbling, grain direction, and how you plan to cook (sear vs braise vs slice thin).
Read the full guides: flap steak (what-is) · tenderloin (what-is) · flap steak hub · tenderloin hub