butterfly
Cut an ingredient (often meat, sometimes bread) nearly in half lengthwise and open it flat, like a book -- used to even out thickness for more consistent cooking, or to create a pocket for stuffing.
How to do it
Place the ingredient on a stable cutting board. For a chicken breast, hold the top gently with your non-knife hand, position the blade parallel to the board, and slice horizontally through the thickest side, stopping just before cutting all the way through the opposite edge -- then open the two halves like a book. If the thickness still isn't even, place the meat between sheets of parchment or plastic wrap and gently pound the thicker areas until it's reasonably uniform.
Common pitfalls
- Cutting all the way through -- that makes two separate pieces instead of one butterflied piece.
- Angling the knife -- uneven halves defeat the whole point.
- Using a dull knife -- it makes a controlled horizontal cut much harder to manage.
- Pounding too aggressively -- excess force tears the muscle fibers instead of just flattening them.
Why it works
Heat enters food mainly through the surface and works its way in gradually, so a thick piece develops a bigger temperature gap between its exterior and its center. Butterflying shortens the distance heat has to travel to reach the middle, which lets the center reach its target temperature before the exterior is badly overcooked. The larger surface area it creates also means more area available for browning and for seasoning to reach.
Equipment
A very sharp chef's, slicing, or boning knife works well -- the blade should move smoothly through the meat without needing heavy downward pressure. A meat mallet is useful for evening out the thickness afterward; a rolling pin or a small heavy pan can substitute, since the goal is flattening, not smashing.