The technique creates a thinner piece of meat that's more easily rolled up.
1. To butterfly and stuff a flank steak, make a lengthwise cut horizontally through steak, cutting to within 1/2 inch of opposite side. Spread open; cover with plastic wrap.
2. Working from the center to the edges, pound with flat side of meat mallet to even thickness (about a 12-inch square).
3. Remove plastic wrap. Sprinkle pepper over entire cut surface; set aside.
5. Roll up so that grain runs lengthwise. Tie in several places with heavy kitchen string. If necessary, cut roll in half to fit pan.
Be careful not to cut completely through the meat or you may wind up with two or three pieces of meat rather than one large, thin one.