perpendicular to the meat. Slice the meat in wide, thin pieces to get tender, chewable pieces.
The grain of the meat should be apparent just by looking. The grain is the linear structure of the meat fiber. Cutting meat the same way the grain runs makes it tough to chew. Cutting the opposite way, against the grain, breaks down the fibers and delivers tender pieces or slices of meat.
While not as crucial to poultry as to meat, carving a large piece of grilled breast is best done against the grain to keep the moisture contained in the meat and not let it escape, as it would if slicing with the grain. Cutting poultry with the grain of the flesh is simply separating the fibers, and doing so releases the moisture which had been resting there.
Observing these few guidelines will ensure that your shopping, storing, preparation, and cooking will not be undone by a slipup just before serving.