How can I evenly grill a thin steak on a skillet?
Thin cut meat will curl if there is an outside perimeter of gristle or silverskin (which there usually is). Those things shrink faster than the meat, causing the curling. Take a pair of kitchen shears or a sharp knife and make tiny cuts (it shouldn't take more than 1/4 inch) every inch or so around the perimeter of the steak, just into the meat itself. That should solve the problem.