Hash is typically a combination of leftover potatoes, meat, and sometimes veggie that is pan fried.
My favorite hash is made with leftover baked or boiled potatoes, sliced or diced with roast beef, chopped, and green onion
My husband’s favorite is with the same potatoes but chopped turkey and no additional veggies. He then pours ketchup on the top of it.
My mom’s Sunday dinner leftovers typically became hash the next day when I was a kid. She made roast beef, potatoes, and carrots in a dutch oven on Sunday and then all of the leftovers were chopped up into hash the next day. If there was not much meat, mom would drop an egg into the frying pan too. There is no need to beat the egg ahead of time, just drop it in when the hash is warm but not quite ready and stir and turn your hash until the egg is set.
Any meat, potatoes, and veggie combo will work. Just use your imagination and plenty of oil (spray oil is fine). Cheese is an excellent garnish.