I am looking for a good recipe to use up leftover pot roast; a hash perhaps?

Also, chop up and toss into fried rice.

Philly cheesesteak route would be yummy too!

Grind up the meat and use it as a ravioli filling. Or shred and add it to your favorite tomato (marinara) sauce for a meat sauce.

Make a beef pot pie. If you have leftover gravy, heat it and get it to the consistency you want--not too thick or thin. You can thin it a bit with some beef broth. Cube your meat and add it with chopped onion and chopped green pepper to taste (green pepper optional--maybe 2 tbsp). You can also chop some green onions and add those (around 1-2 tbsp). Add cooked cubed red potato, cooked green beans, and another vegetable if you like (I've used baby peas or tiny white frozen corn). Cook it, stirring, until it begins to bubble. Cool. Depending on what casserole dish you are using, fit pie crust over the top of the mixture (should have said to pour it first into a casserole) and crimp and vent. At this point you can refrigerate it for a few hours until baking, or bake immediately at 350 for 30-45 minutes or until crust is browned and the mixture is bubbling up through the crust.
This is something my mother always made with beef roast leftovers. It may sound odd, but actually it's delicious and comforting on a cold day.

You could braise it in barbecue sauce (try Dead Guy Sauce on this site.) till it's falling apart and make barbecued beef sandwiches.

Shred the meat and use it for tacos or take your favorite pulled pork sandwich recipe and substitute with your pot roast meat