Freeze steaks for 45 minutes or so until they are firm and partially frozen, then remove excess fat and slice very thin; place in a large bowl or resealable plastic bag.
In a small skillet, toast sesame seeds over high heat, swirling pan, being careful not to burn; remove from heat and cool.
Place sesame seeds in a mortar and grind finely (but do not grind into a paste) or you may use a small coffee grinder set on pulse.