Heat vegetable oil in a heavy (or cast iron) skillet over medium-high heat. Add onion and red bell pepper, and spread into a single layer. Season with pepper and ¼ teaspoon salt. Let cook 7 minutes without stirring, until the onions are turning translucent and the vegetables are starting to brown. Stir and cook a few more minutes if necessary.
Stir in potatoes and beef. Season with pepper and another ¼ teaspoon salt. Let cook without stirring for 5 minutes to brown the bottom.
Check the bottom of a section of the hash to see if it's browned. If it hasn't browned much, smooth it back and cook for another 3-5 minutes before checking another section. Beef that includes a lot of liquid will make the hash take longer to brown on bottom.
Once some of the hash has browned, pour over the water, which will sizzle when it hits the pan. Flip sections of the hash to get the browned bits on bottom to the top. Browned bits should scrape up easily; if not, add a tablespoon of water one at a time until they do.
Sprinkle with pepper and the remaining ¼ teaspoon salt and give everything another stir. Cook until there's no water on bottom, but the hash still looks moist. Serve immediately.
Notes
This recipe is developed for leftovers. I cannot recommend using uncooked beef or potatoes as it would dramatically change the cooking time. Much flavor comes from cooking the onion and pepper at the beginning; do not stir or rush this process.I use ¾ teaspoon table salt if using water and minimally seasoned beef and potatoes. Add salt only at the end if using broth or if your beef and potatoes are highly salted.Calorie count is an estimate only and will vary. Adapted from an old recipe on AllRecipes.