While the potatoes cook, prepare the rivels. In a medium bowl, combine the flour, egg, and a pinch of salt. Mix the ingredients with your hands until small, crumbly pieces form. These are your rivels.
Add The Rivels To The Soup
Once the potatoes are tender, use a potato masher to lightly mash some of the potatoes directly in the pot. This thickens the soup while still leaving chunks. Gradually sprinkle the rivels into the simmering soup, stirring gently to prevent clumping. Simmer for 10 minutes, stirring occasionally, until the rivels are cooked through.
Finish The Soup
Stir in the milk (or heavy cream) and heat gently, ensuring the soup does not boil. Season with salt and black pepper to taste.
Serve And Enjoy
Ladle the soup into bowls and serve it hot. A slice of crusty bread on the side makes it even better.