How do I deal with silverskin in a steak without trimming away all the fat?
A good Sirloin (New York Strip steak) has a reasonable marble of fat, so you should not have to worry about edge fat

If you like your fat, pull/trim the silverskin and fat off and render the fat in a medium hot pan BEFORE putting the steak in. When enough fat has melted for your taste, cook the steak in the fat at the temperature and time you like

Add fresh herbs or garlic to the rendering fat for extra zing!