Dad's Potato Soup

Place the potato cubes, celery, and onion into a pressure cooker and add 4 cups of water, or enough to reach the fullness mark on your cooker. (Follow manufacturer's directions for how full to fill your cooker.) Cover the cooker, seal, and bring the pressure up over medium heat. When cooker reaches full pressure, reduce heat to maintain the pressure, and pressure-cook the vegetables for 25 minutes.

Allow the pressure in the cooker to subside, and release the cover on the cooker when the pressure is normal. Mix in the evaporated milk, butter, salt, and black pepper, and bring the soup to a boil over medium heat. Reduce heat to a simmer, and cook the soup to the desired thickness, 5 to 15 minutes. If you like a thicker soup, mix in mashed potato flakes to desired consistency.