Flap Steak vs Tendon — What's the Difference?
Quick Answer
Flap Steak (flap steak (sirloin flap)) and Tendon (beef tendon) are not the same cut: Flap Steak is sirloin primal (Bottom sirloin, obliquus internus abdominis muscle); Tendon is offal primal (Connective tissue at joints — particularly the hock/lower leg).
Canonical entities: Flap Steak · Tendon
Side-by-side
| flap steak | tendon | |
|---|---|---|
| Primal | sirloin | offal |
| Muscle / location | Bottom sirloin, obliquus internus abdominis muscle | Connective tissue at joints — particularly the hock/lower leg |
| 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. | Collagen-rich connective tissue extracted from the leg joints, particularly the Achilles tendon area. Extremely gelatinous when slow-cooked; provides body and sticky texture to braises and soups. Prized in Korean, Vietnamese, and South Asian cuisine for its chew and the richness it adds to broth. |
Key differences
- Different primals: sirloin vs offal.
- 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.
Tendon
Pick Tendon when its primal/muscle traits fit the dish: Collagen-rich connective tissue extracted from the leg joints, particularly the Achilles tendon area. Extremely gelatinous when slow-cooked; provides body and sticky texture to braises and soups. Prized in Korean, Vietnamese, and South Asian cuisine for its chew and the richness it adds to broth.
Flap Steak and Tendon are different canonical muscles/primals: Flap Steak is sirloin (Bottom sirloin, obliquus internus abdominis muscle); Tendon is offal (Connective tissue at joints — particularly the hock/lower leg).
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) · tendon (what-is) · flap steak hub · tendon hub