It takes patience to get crispy hash. In a heavy skillet (preferably not a non-stick skillet) over medium heat, spread the hash in an even layer and do not disturb for 5 minutes. With a spatula, lift up a corner of the hash to see if it has developed a crust. If it hasn’t, cook a few minutes longer. If it has developed a crust, turn over the hash and cook 3 to 4 minutes or until a crispy crust has formed on both sides.