Performance vehicles are usually modified (if necessary) so that the heights of the brake and accelerator pedals are closely matched to permit easy use of heel-and-toe, and that the pedals are not too far apart.
The technique involves operating the brake with the left edge of the foot, while rocking it down and to the right to operate the throttle. With practice, it becomes possible to smoothly and independently operate both pedals with one foot. The technique is common in all forms of motorsport, especially rallying.
An unrelated technique, called left-foot braking should not be confused with heel-and-toe.